1 /* 2 * Copyright (c) 2013, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.lang; 27 28 import java.io.InputStream; 29 import java.io.IOException; 30 import java.io.UncheckedIOException; 31 import java.io.File; 32 import java.lang.reflect.Constructor; 33 import java.lang.reflect.InvocationTargetException; 34 import java.net.URL; 35 import java.security.AccessController; 36 import java.security.AccessControlContext; 37 import java.security.CodeSource; 38 import java.security.PrivilegedAction; 39 import java.security.ProtectionDomain; 40 import java.security.cert.Certificate; 41 import java.util.ArrayDeque; 42 import java.util.Arrays; 43 import java.util.Collections; 44 import java.util.Deque; 45 import java.util.Enumeration; 46 import java.util.HashMap; 47 import java.util.HashSet; 48 import java.util.Hashtable; 49 import java.util.Map; 50 import java.util.NoSuchElementException; 51 import java.util.Objects; 52 import java.util.Set; 53 import java.util.Spliterator; 54 import java.util.Spliterators; 55 import java.util.Vector; 56 import java.util.WeakHashMap; 57 import java.util.concurrent.ConcurrentHashMap; 58 import java.util.function.Supplier; 59 import java.util.stream.Stream; 60 import java.util.stream.StreamSupport; 61 62 import jdk.internal.loader.BuiltinClassLoader; 63 import jdk.internal.perf.PerfCounter; 64 import jdk.internal.loader.BootLoader; 65 import jdk.internal.loader.ClassLoaders; 66 import jdk.internal.misc.Unsafe; 67 import jdk.internal.misc.VM; 68 import jdk.internal.ref.CleanerFactory; 69 import jdk.internal.reflect.CallerSensitive; 70 import jdk.internal.reflect.Reflection; 71 import sun.reflect.misc.ReflectUtil; 72 import sun.security.util.SecurityConstants; 73 74 /** 75 * A class loader is an object that is responsible for loading classes. The 76 * class {@code ClassLoader} is an abstract class. Given the <a 77 * href="#binary-name">binary name</a> of a class, a class loader should attempt to 78 * locate or generate data that constitutes a definition for the class. A 79 * typical strategy is to transform the name into a file name and then read a 80 * "class file" of that name from a file system. 81 * 82 * <p> Every {@link java.lang.Class Class} object contains a {@link 83 * Class#getClassLoader() reference} to the {@code ClassLoader} that defined 84 * it. 85 * 86 * <p> {@code Class} objects for array classes are not created by class 87 * loaders, but are created automatically as required by the Java runtime. 88 * The class loader for an array class, as returned by {@link 89 * Class#getClassLoader()} is the same as the class loader for its element 90 * type; if the element type is a primitive type, then the array class has no 91 * class loader. 92 * 93 * <p> Applications implement subclasses of {@code ClassLoader} in order to 94 * extend the manner in which the Java virtual machine dynamically loads 95 * classes. 96 * 97 * <p> Class loaders may typically be used by security managers to indicate 98 * security domains. 99 * 100 * <p> In addition to loading classes, a class loader is also responsible for 101 * locating resources. A resource is some data (a "{@code .class}" file, 102 * configuration data, or an image for example) that is identified with an 103 * abstract '/'-separated path name. Resources are typically packaged with an 104 * application or library so that they can be located by code in the 105 * application or library. In some cases, the resources are included so that 106 * they can be located by other libraries. 107 * 108 * <p> The {@code ClassLoader} class uses a delegation model to search for 109 * classes and resources. Each instance of {@code ClassLoader} has an 110 * associated parent class loader. When requested to find a class or 111 * resource, a {@code ClassLoader} instance will usually delegate the search 112 * for the class or resource to its parent class loader before attempting to 113 * find the class or resource itself. 114 * 115 * <p> Class loaders that support concurrent loading of classes are known as 116 * <em>{@linkplain #isRegisteredAsParallelCapable() parallel capable}</em> class 117 * loaders and are required to register themselves at their class initialization 118 * time by invoking the {@link 119 * #registerAsParallelCapable ClassLoader.registerAsParallelCapable} 120 * method. Note that the {@code ClassLoader} class is registered as parallel 121 * capable by default. However, its subclasses still need to register themselves 122 * if they are parallel capable. 123 * In environments in which the delegation model is not strictly 124 * hierarchical, class loaders need to be parallel capable, otherwise class 125 * loading can lead to deadlocks because the loader lock is held for the 126 * duration of the class loading process (see {@link #loadClass 127 * loadClass} methods). 128 * 129 * <h2> <a id="builtinLoaders">Run-time Built-in Class Loaders</a></h2> 130 * 131 * The Java run-time has the following built-in class loaders: 132 * 133 * <ul> 134 * <li><p>Bootstrap class loader. 135 * It is the virtual machine's built-in class loader, typically represented 136 * as {@code null}, and does not have a parent.</li> 137 * <li><p>{@linkplain #getPlatformClassLoader() Platform class loader}. 138 * All <em>platform classes</em> are visible to the platform class loader 139 * that can be used as the parent of a {@code ClassLoader} instance. 140 * Platform classes include Java SE platform APIs, their implementation 141 * classes and JDK-specific run-time classes that are defined by the 142 * platform class loader or its ancestors. 143 * <p> To allow for upgrading/overriding of modules defined to the platform 144 * class loader, and where upgraded modules read modules defined to class 145 * loaders other than the platform class loader and its ancestors, then 146 * the platform class loader may have to delegate to other class loaders, 147 * the application class loader for example. 148 * In other words, classes in named modules defined to class loaders 149 * other than the platform class loader and its ancestors may be visible 150 * to the platform class loader. </li> 151 * <li><p>{@linkplain #getSystemClassLoader() System class loader}. 152 * It is also known as <em>application class loader</em> and is distinct 153 * from the platform class loader. 154 * The system class loader is typically used to define classes on the 155 * application class path, module path, and JDK-specific tools. 156 * The platform class loader is a parent or an ancestor of the system class 157 * loader that all platform classes are visible to it.</li> 158 * </ul> 159 * 160 * <p> Normally, the Java virtual machine loads classes from the local file 161 * system in a platform-dependent manner. 162 * However, some classes may not originate from a file; they may originate 163 * from other sources, such as the network, or they could be constructed by an 164 * application. The method {@link #defineClass(String, byte[], int, int) 165 * defineClass} converts an array of bytes into an instance of class 166 * {@code Class}. Instances of this newly defined class can be created using 167 * {@link Class#newInstance Class.newInstance}. 168 * 169 * <p> The methods and constructors of objects created by a class loader may 170 * reference other classes. To determine the class(es) referred to, the Java 171 * virtual machine invokes the {@link #loadClass loadClass} method of 172 * the class loader that originally created the class. 173 * 174 * <p> For example, an application could create a network class loader to 175 * download class files from a server. Sample code might look like: 176 * 177 * <blockquote><pre> 178 * ClassLoader loader = new NetworkClassLoader(host, port); 179 * Object main = loader.loadClass("Main", true).newInstance(); 180 * . . . 181 * </pre></blockquote> 182 * 183 * <p> The network class loader subclass must define the methods {@link 184 * #findClass findClass} and {@code loadClassData} to load a class 185 * from the network. Once it has downloaded the bytes that make up the class, 186 * it should use the method {@link #defineClass defineClass} to 187 * create a class instance. A sample implementation is: 188 * 189 * <blockquote><pre> 190 * class NetworkClassLoader extends ClassLoader { 191 * String host; 192 * int port; 193 * 194 * public Class findClass(String name) { 195 * byte[] b = loadClassData(name); 196 * return defineClass(name, b, 0, b.length); 197 * } 198 * 199 * private byte[] loadClassData(String name) { 200 * // load the class data from the connection 201 * . . . 202 * } 203 * } 204 * </pre></blockquote> 205 * 206 * <h3> <a id="binary-name">Binary names</a> </h3> 207 * 208 * <p> Any class name provided as a {@code String} parameter to methods in 209 * {@code ClassLoader} must be a binary name as defined by 210 * <cite>The Java™ Language Specification</cite>. 211 * 212 * <p> Examples of valid class names include: 213 * <blockquote><pre> 214 * "java.lang.String" 215 * "javax.swing.JSpinner$DefaultEditor" 216 * "java.security.KeyStore$Builder$FileBuilder$1" 217 * "java.net.URLClassLoader$3$1" 218 * </pre></blockquote> 219 * 220 * <p> Any package name provided as a {@code String} parameter to methods in 221 * {@code ClassLoader} must be either the empty string (denoting an unnamed package) 222 * or a fully qualified name as defined by 223 * <cite>The Java™ Language Specification</cite>. 224 * 225 * @jls 6.7 Fully Qualified Names 226 * @jls 13.1 The Form of a Binary 227 * @see #resolveClass(Class) 228 * @since 1.0 229 * @revised 9 230 * @spec JPMS 231 */ 232 public abstract class ClassLoader { 233 234 private static native void registerNatives(); 235 static { 236 registerNatives(); 237 } 238 239 // The parent class loader for delegation 240 // Note: VM hardcoded the offset of this field, thus all new fields 241 // must be added *after* it. 242 private final ClassLoader parent; 243 244 // class loader name 245 private final String name; 246 247 // the unnamed module for this ClassLoader 248 private final Module unnamedModule; 249 250 // a string for exception message printing 251 private final String nameAndId; 252 253 /** 254 * Encapsulates the set of parallel capable loader types. 255 */ 256 private static class ParallelLoaders { 257 private ParallelLoaders() {} 258 259 // the set of parallel capable loader types 260 private static final Set<Class<? extends ClassLoader>> loaderTypes = 261 Collections.newSetFromMap(new WeakHashMap<>()); 262 static { 263 synchronized (loaderTypes) { loaderTypes.add(ClassLoader.class); } 264 } 265 266 /** 267 * Registers the given class loader type as parallel capable. 268 * Returns {@code true} is successfully registered; {@code false} if 269 * loader's super class is not registered. 270 */ 271 static boolean register(Class<? extends ClassLoader> c) { 272 synchronized (loaderTypes) { 273 if (loaderTypes.contains(c.getSuperclass())) { 274 // register the class loader as parallel capable 275 // if and only if all of its super classes are. 276 // Note: given current classloading sequence, if 277 // the immediate super class is parallel capable, 278 // all the super classes higher up must be too. 279 loaderTypes.add(c); 280 return true; 281 } else { 282 return false; 283 } 284 } 285 } 286 287 /** 288 * Returns {@code true} if the given class loader type is 289 * registered as parallel capable. 290 */ 291 static boolean isRegistered(Class<? extends ClassLoader> c) { 292 synchronized (loaderTypes) { 293 return loaderTypes.contains(c); 294 } 295 } 296 } 297 298 // Maps class name to the corresponding lock object when the current 299 // class loader is parallel capable. 300 // Note: VM also uses this field to decide if the current class loader 301 // is parallel capable and the appropriate lock object for class loading. 302 private final ConcurrentHashMap<String, Object> parallelLockMap; 303 304 // Maps packages to certs 305 private final Map <String, Certificate[]> package2certs; 306 307 // Shared among all packages with unsigned classes 308 private static final Certificate[] nocerts = new Certificate[0]; 309 310 // The classes loaded by this class loader. The only purpose of this table 311 // is to keep the classes from being GC'ed until the loader is GC'ed. 312 private final Vector<Class<?>> classes = new Vector<>(); 313 314 // The "default" domain. Set as the default ProtectionDomain on newly 315 // created classes. 316 private final ProtectionDomain defaultDomain = 317 new ProtectionDomain(new CodeSource(null, (Certificate[]) null), 318 null, this, null); 319 320 // Invoked by the VM to record every loaded class with this loader. 321 void addClass(Class<?> c) { 322 classes.addElement(c); 323 } 324 325 // The packages defined in this class loader. Each package name is 326 // mapped to its corresponding NamedPackage object. 327 // 328 // The value is a Package object if ClassLoader::definePackage, 329 // Class::getPackage, ClassLoader::getDefinePackage(s) or 330 // Package::getPackage(s) method is called to define it. 331 // Otherwise, the value is a NamedPackage object. 332 private final ConcurrentHashMap<String, NamedPackage> packages 333 = new ConcurrentHashMap<>(); 334 335 /* 336 * Returns a named package for the given module. 337 */ 338 private NamedPackage getNamedPackage(String pn, Module m) { 339 NamedPackage p = packages.get(pn); 340 if (p == null) { 341 p = new NamedPackage(pn, m); 342 343 NamedPackage value = packages.putIfAbsent(pn, p); 344 if (value != null) { 345 // Package object already be defined for the named package 346 p = value; 347 // if definePackage is called by this class loader to define 348 // a package in a named module, this will return Package 349 // object of the same name. Package object may contain 350 // unexpected information but it does not impact the runtime. 351 // this assertion may be helpful for troubleshooting 352 assert value.module() == m; 353 } 354 } 355 return p; 356 } 357 358 private static Void checkCreateClassLoader() { 359 return checkCreateClassLoader(null); 360 } 361 362 private static Void checkCreateClassLoader(String name) { 363 if (name != null && name.isEmpty()) { 364 throw new IllegalArgumentException("name must be non-empty or null"); 365 } 366 367 SecurityManager security = System.getSecurityManager(); 368 if (security != null) { 369 security.checkCreateClassLoader(); 370 } 371 return null; 372 } 373 374 private ClassLoader(Void unused, String name, ClassLoader parent) { 375 this.name = name; 376 this.parent = parent; 377 this.unnamedModule = new Module(this); 378 if (ParallelLoaders.isRegistered(this.getClass())) { 379 parallelLockMap = new ConcurrentHashMap<>(); 380 package2certs = new ConcurrentHashMap<>(); 381 assertionLock = new Object(); 382 } else { 383 // no finer-grained lock; lock on the classloader instance 384 parallelLockMap = null; 385 package2certs = new Hashtable<>(); 386 assertionLock = this; 387 } 388 this.nameAndId = nameAndId(this); 389 } 390 391 /** 392 * If the defining loader has a name explicitly set then 393 * '<loader-name>' @<id> 394 * If the defining loader has no name then 395 * <qualified-class-name> @<id> 396 * If it's built-in loader then omit `@<id>` as there is only one instance. 397 */ 398 private static String nameAndId(ClassLoader ld) { 399 String nid = ld.getName() != null ? "\'" + ld.getName() + "\'" 400 : ld.getClass().getName(); 401 if (!(ld instanceof BuiltinClassLoader)) { 402 String id = Integer.toHexString(System.identityHashCode(ld)); 403 nid = nid + " @" + id; 404 } 405 return nid; 406 } 407 408 /** 409 * Creates a new class loader of the specified name and using the 410 * specified parent class loader for delegation. 411 * 412 * @apiNote If the parent is specified as {@code null} (for the 413 * bootstrap class loader) then there is no guarantee that all platform 414 * classes are visible. 415 * 416 * @param name class loader name; or {@code null} if not named 417 * @param parent the parent class loader 418 * 419 * @throws IllegalArgumentException if the given name is empty. 420 * 421 * @throws SecurityException 422 * If a security manager exists and its 423 * {@link SecurityManager#checkCreateClassLoader()} 424 * method doesn't allow creation of a new class loader. 425 * 426 * @since 9 427 * @spec JPMS 428 */ 429 protected ClassLoader(String name, ClassLoader parent) { 430 this(checkCreateClassLoader(name), name, parent); 431 } 432 433 /** 434 * Creates a new class loader using the specified parent class loader for 435 * delegation. 436 * 437 * <p> If there is a security manager, its {@link 438 * SecurityManager#checkCreateClassLoader() checkCreateClassLoader} method 439 * is invoked. This may result in a security exception. </p> 440 * 441 * @apiNote If the parent is specified as {@code null} (for the 442 * bootstrap class loader) then there is no guarantee that all platform 443 * classes are visible. 444 * 445 * @param parent 446 * The parent class loader 447 * 448 * @throws SecurityException 449 * If a security manager exists and its 450 * {@code checkCreateClassLoader} method doesn't allow creation 451 * of a new class loader. 452 * 453 * @since 1.2 454 */ 455 protected ClassLoader(ClassLoader parent) { 456 this(checkCreateClassLoader(), null, parent); 457 } 458 459 /** 460 * Creates a new class loader using the {@code ClassLoader} returned by 461 * the method {@link #getSystemClassLoader() 462 * getSystemClassLoader()} as the parent class loader. 463 * 464 * <p> If there is a security manager, its {@link 465 * SecurityManager#checkCreateClassLoader() 466 * checkCreateClassLoader} method is invoked. This may result in 467 * a security exception. </p> 468 * 469 * @throws SecurityException 470 * If a security manager exists and its 471 * {@code checkCreateClassLoader} method doesn't allow creation 472 * of a new class loader. 473 */ 474 protected ClassLoader() { 475 this(checkCreateClassLoader(), null, getSystemClassLoader()); 476 } 477 478 /** 479 * Returns the name of this class loader or {@code null} if 480 * this class loader is not named. 481 * 482 * @apiNote This method is non-final for compatibility. If this 483 * method is overridden, this method must return the same name 484 * as specified when this class loader was instantiated. 485 * 486 * @return name of this class loader; or {@code null} if 487 * this class loader is not named. 488 * 489 * @since 9 490 * @spec JPMS 491 */ 492 public String getName() { 493 return name; 494 } 495 496 // package-private used by StackTraceElement to avoid 497 // calling the overrideable getName method 498 final String name() { 499 return name; 500 } 501 502 // -- Class -- 503 504 /** 505 * Loads the class with the specified <a href="#binary-name">binary name</a>. 506 * This method searches for classes in the same manner as the {@link 507 * #loadClass(String, boolean)} method. It is invoked by the Java virtual 508 * machine to resolve class references. Invoking this method is equivalent 509 * to invoking {@link #loadClass(String, boolean) loadClass(name, 510 * false)}. 511 * 512 * @param name 513 * The <a href="#binary-name">binary name</a> of the class 514 * 515 * @return The resulting {@code Class} object 516 * 517 * @throws ClassNotFoundException 518 * If the class was not found 519 */ 520 public Class<?> loadClass(String name) throws ClassNotFoundException { 521 return loadClass(name, false); 522 } 523 524 /** 525 * Loads the class with the specified <a href="#binary-name">binary name</a>. The 526 * default implementation of this method searches for classes in the 527 * following order: 528 * 529 * <ol> 530 * 531 * <li><p> Invoke {@link #findLoadedClass(String)} to check if the class 532 * has already been loaded. </p></li> 533 * 534 * <li><p> Invoke the {@link #loadClass(String) loadClass} method 535 * on the parent class loader. If the parent is {@code null} the class 536 * loader built into the virtual machine is used, instead. </p></li> 537 * 538 * <li><p> Invoke the {@link #findClass(String)} method to find the 539 * class. </p></li> 540 * 541 * </ol> 542 * 543 * <p> If the class was found using the above steps, and the 544 * {@code resolve} flag is true, this method will then invoke the {@link 545 * #resolveClass(Class)} method on the resulting {@code Class} object. 546 * 547 * <p> Subclasses of {@code ClassLoader} are encouraged to override {@link 548 * #findClass(String)}, rather than this method. </p> 549 * 550 * <p> Unless overridden, this method synchronizes on the result of 551 * {@link #getClassLoadingLock getClassLoadingLock} method 552 * during the entire class loading process. 553 * 554 * @param name 555 * The <a href="#binary-name">binary name</a> of the class 556 * 557 * @param resolve 558 * If {@code true} then resolve the class 559 * 560 * @return The resulting {@code Class} object 561 * 562 * @throws ClassNotFoundException 563 * If the class could not be found 564 */ 565 protected Class<?> loadClass(String name, boolean resolve) 566 throws ClassNotFoundException 567 { 568 synchronized (getClassLoadingLock(name)) { 569 // First, check if the class has already been loaded 570 Class<?> c = findLoadedClass(name); 571 if (c == null) { 572 long t0 = System.nanoTime(); 573 try { 574 if (parent != null) { 575 c = parent.loadClass(name, false); 576 } else { 577 c = findBootstrapClassOrNull(name); 578 } 579 } catch (ClassNotFoundException e) { 580 // ClassNotFoundException thrown if class not found 581 // from the non-null parent class loader 582 } 583 584 if (c == null) { 585 // If still not found, then invoke findClass in order 586 // to find the class. 587 long t1 = System.nanoTime(); 588 c = findClass(name); 589 590 // this is the defining class loader; record the stats 591 PerfCounter.getParentDelegationTime().addTime(t1 - t0); 592 PerfCounter.getFindClassTime().addElapsedTimeFrom(t1); 593 PerfCounter.getFindClasses().increment(); 594 } 595 } 596 if (resolve) { 597 resolveClass(c); 598 } 599 return c; 600 } 601 } 602 603 /** 604 * Loads the class with the specified <a href="#binary-name">binary name</a> 605 * in a module defined to this class loader. This method returns {@code null} 606 * if the class could not be found. 607 * 608 * @apiNote This method does not delegate to the parent class loader. 609 * 610 * @implSpec The default implementation of this method searches for classes 611 * in the following order: 612 * 613 * <ol> 614 * <li>Invoke {@link #findLoadedClass(String)} to check if the class 615 * has already been loaded.</li> 616 * <li>Invoke the {@link #findClass(String, String)} method to find the 617 * class in the given module.</li> 618 * </ol> 619 * 620 * @param module 621 * The module 622 * @param name 623 * The <a href="#binary-name">binary name</a> of the class 624 * 625 * @return The resulting {@code Class} object in a module defined by 626 * this class loader, or {@code null} if the class could not be found. 627 */ 628 final Class<?> loadClass(Module module, String name) { 629 synchronized (getClassLoadingLock(name)) { 630 // First, check if the class has already been loaded 631 Class<?> c = findLoadedClass(name); 632 if (c == null) { 633 c = findClass(module.getName(), name); 634 } 635 if (c != null && c.getModule() == module) { 636 return c; 637 } else { 638 return null; 639 } 640 } 641 } 642 643 /** 644 * Returns the lock object for class loading operations. 645 * For backward compatibility, the default implementation of this method 646 * behaves as follows. If this ClassLoader object is registered as 647 * parallel capable, the method returns a dedicated object associated 648 * with the specified class name. Otherwise, the method returns this 649 * ClassLoader object. 650 * 651 * @param className 652 * The name of the to-be-loaded class 653 * 654 * @return the lock for class loading operations 655 * 656 * @throws NullPointerException 657 * If registered as parallel capable and {@code className} is null 658 * 659 * @see #loadClass(String, boolean) 660 * 661 * @since 1.7 662 */ 663 protected Object getClassLoadingLock(String className) { 664 Object lock = this; 665 if (parallelLockMap != null) { 666 Object newLock = new Object(); 667 lock = parallelLockMap.putIfAbsent(className, newLock); 668 if (lock == null) { 669 lock = newLock; 670 } 671 } 672 return lock; 673 } 674 675 // Invoked by the VM after loading class with this loader. 676 private void checkPackageAccess(Class<?> cls, ProtectionDomain pd) { 677 final SecurityManager sm = System.getSecurityManager(); 678 if (sm != null) { 679 if (ReflectUtil.isNonPublicProxyClass(cls)) { 680 for (Class<?> intf: cls.getInterfaces()) { 681 checkPackageAccess(intf, pd); 682 } 683 return; 684 } 685 686 final String packageName = cls.getPackageName(); 687 if (!packageName.isEmpty()) { 688 AccessController.doPrivileged(new PrivilegedAction<>() { 689 public Void run() { 690 sm.checkPackageAccess(packageName); 691 return null; 692 } 693 }, new AccessControlContext(new ProtectionDomain[] {pd})); 694 } 695 } 696 } 697 698 /** 699 * Finds the class with the specified <a href="#binary-name">binary name</a>. 700 * This method should be overridden by class loader implementations that 701 * follow the delegation model for loading classes, and will be invoked by 702 * the {@link #loadClass loadClass} method after checking the 703 * parent class loader for the requested class. 704 * 705 * @implSpec The default implementation throws {@code ClassNotFoundException}. 706 * 707 * @param name 708 * The <a href="#binary-name">binary name</a> of the class 709 * 710 * @return The resulting {@code Class} object 711 * 712 * @throws ClassNotFoundException 713 * If the class could not be found 714 * 715 * @since 1.2 716 */ 717 protected Class<?> findClass(String name) throws ClassNotFoundException { 718 throw new ClassNotFoundException(name); 719 } 720 721 /** 722 * Finds the class with the given <a href="#binary-name">binary name</a> 723 * in a module defined to this class loader. 724 * Class loader implementations that support loading from modules 725 * should override this method. 726 * 727 * @apiNote This method returns {@code null} rather than throwing 728 * {@code ClassNotFoundException} if the class could not be found. 729 * 730 * @implSpec The default implementation attempts to find the class by 731 * invoking {@link #findClass(String)} when the {@code moduleName} is 732 * {@code null}. It otherwise returns {@code null}. 733 * 734 * @param moduleName 735 * The module name; or {@code null} to find the class in the 736 * {@linkplain #getUnnamedModule() unnamed module} for this 737 * class loader 738 739 * @param name 740 * The <a href="#binary-name">binary name</a> of the class 741 * 742 * @return The resulting {@code Class} object, or {@code null} 743 * if the class could not be found. 744 * 745 * @since 9 746 * @spec JPMS 747 */ 748 protected Class<?> findClass(String moduleName, String name) { 749 if (moduleName == null) { 750 try { 751 return findClass(name); 752 } catch (ClassNotFoundException ignore) { } 753 } 754 return null; 755 } 756 757 758 /** 759 * Converts an array of bytes into an instance of class {@code Class}. 760 * Before the {@code Class} can be used it must be resolved. This method 761 * is deprecated in favor of the version that takes a <a 762 * href="#binary-name">binary name</a> as its first argument, and is more secure. 763 * 764 * @param b 765 * The bytes that make up the class data. The bytes in positions 766 * {@code off} through {@code off+len-1} should have the format 767 * of a valid class file as defined by 768 * <cite>The Java™ Virtual Machine Specification</cite>. 769 * 770 * @param off 771 * The start offset in {@code b} of the class data 772 * 773 * @param len 774 * The length of the class data 775 * 776 * @return The {@code Class} object that was created from the specified 777 * class data 778 * 779 * @throws ClassFormatError 780 * If the data did not contain a valid class 781 * 782 * @throws IndexOutOfBoundsException 783 * If either {@code off} or {@code len} is negative, or if 784 * {@code off+len} is greater than {@code b.length}. 785 * 786 * @throws SecurityException 787 * If an attempt is made to add this class to a package that 788 * contains classes that were signed by a different set of 789 * certificates than this class, or if an attempt is made 790 * to define a class in a package with a fully-qualified name 791 * that starts with "{@code java.}". 792 * 793 * @see #loadClass(String, boolean) 794 * @see #resolveClass(Class) 795 * 796 * @deprecated Replaced by {@link #defineClass(String, byte[], int, int) 797 * defineClass(String, byte[], int, int)} 798 */ 799 @Deprecated(since="1.1") 800 protected final Class<?> defineClass(byte[] b, int off, int len) 801 throws ClassFormatError 802 { 803 return defineClass(null, b, off, len, null); 804 } 805 806 /** 807 * Converts an array of bytes into an instance of class {@code Class}. 808 * Before the {@code Class} can be used it must be resolved. 809 * 810 * <p> This method assigns a default {@link java.security.ProtectionDomain 811 * ProtectionDomain} to the newly defined class. The 812 * {@code ProtectionDomain} is effectively granted the same set of 813 * permissions returned when {@link 814 * java.security.Policy#getPermissions(java.security.CodeSource) 815 * Policy.getPolicy().getPermissions(new CodeSource(null, null))} 816 * is invoked. The default protection domain is created on the first invocation 817 * of {@link #defineClass(String, byte[], int, int) defineClass}, 818 * and re-used on subsequent invocations. 819 * 820 * <p> To assign a specific {@code ProtectionDomain} to the class, use 821 * the {@link #defineClass(String, byte[], int, int, 822 * java.security.ProtectionDomain) defineClass} method that takes a 823 * {@code ProtectionDomain} as one of its arguments. </p> 824 * 825 * <p> 826 * This method defines a package in this class loader corresponding to the 827 * package of the {@code Class} (if such a package has not already been defined 828 * in this class loader). The name of the defined package is derived from 829 * the <a href="#binary-name">binary name</a> of the class specified by 830 * the byte array {@code b}. 831 * Other properties of the defined package are as specified by {@link Package}. 832 * 833 * @param name 834 * The expected <a href="#binary-name">binary name</a> of the class, or 835 * {@code null} if not known 836 * 837 * @param b 838 * The bytes that make up the class data. The bytes in positions 839 * {@code off} through {@code off+len-1} should have the format 840 * of a valid class file as defined by 841 * <cite>The Java™ Virtual Machine Specification</cite>. 842 * 843 * @param off 844 * The start offset in {@code b} of the class data 845 * 846 * @param len 847 * The length of the class data 848 * 849 * @return The {@code Class} object that was created from the specified 850 * class data. 851 * 852 * @throws ClassFormatError 853 * If the data did not contain a valid class 854 * 855 * @throws IndexOutOfBoundsException 856 * If either {@code off} or {@code len} is negative, or if 857 * {@code off+len} is greater than {@code b.length}. 858 * 859 * @throws SecurityException 860 * If an attempt is made to add this class to a package that 861 * contains classes that were signed by a different set of 862 * certificates than this class (which is unsigned), or if 863 * {@code name} begins with "{@code java.}". 864 * 865 * @see #loadClass(String, boolean) 866 * @see #resolveClass(Class) 867 * @see java.security.CodeSource 868 * @see java.security.SecureClassLoader 869 * 870 * @since 1.1 871 * @revised 9 872 * @spec JPMS 873 */ 874 protected final Class<?> defineClass(String name, byte[] b, int off, int len) 875 throws ClassFormatError 876 { 877 return defineClass(name, b, off, len, null); 878 } 879 880 /* Determine protection domain, and check that: 881 - not define java.* class, 882 - signer of this class matches signers for the rest of the classes in 883 package. 884 */ 885 private ProtectionDomain preDefineClass(String name, 886 ProtectionDomain pd) 887 { 888 if (!checkName(name)) 889 throw new NoClassDefFoundError("IllegalName: " + name); 890 891 // Note: Checking logic in java.lang.invoke.MemberName.checkForTypeAlias 892 // relies on the fact that spoofing is impossible if a class has a name 893 // of the form "java.*" 894 if ((name != null) && name.startsWith("java.") 895 && this != getBuiltinPlatformClassLoader()) { 896 throw new SecurityException 897 ("Prohibited package name: " + 898 name.substring(0, name.lastIndexOf('.'))); 899 } 900 if (pd == null) { 901 pd = defaultDomain; 902 } 903 904 if (name != null) { 905 checkCerts(name, pd.getCodeSource()); 906 } 907 908 return pd; 909 } 910 911 private String defineClassSourceLocation(ProtectionDomain pd) { 912 CodeSource cs = pd.getCodeSource(); 913 String source = null; 914 if (cs != null && cs.getLocation() != null) { 915 source = cs.getLocation().toString(); 916 } 917 return source; 918 } 919 920 private void postDefineClass(Class<?> c, ProtectionDomain pd) { 921 // define a named package, if not present 922 getNamedPackage(c.getPackageName(), c.getModule()); 923 924 if (pd.getCodeSource() != null) { 925 Certificate certs[] = pd.getCodeSource().getCertificates(); 926 if (certs != null) 927 setSigners(c, certs); 928 } 929 } 930 931 /** 932 * Converts an array of bytes into an instance of class {@code Class}, 933 * with a given {@code ProtectionDomain}. 934 * 935 * <p> If the given {@code ProtectionDomain} is {@code null}, 936 * then a default protection domain will be assigned to the class as specified 937 * in the documentation for {@link #defineClass(String, byte[], int, int)}. 938 * Before the class can be used it must be resolved. 939 * 940 * <p> The first class defined in a package determines the exact set of 941 * certificates that all subsequent classes defined in that package must 942 * contain. The set of certificates for a class is obtained from the 943 * {@link java.security.CodeSource CodeSource} within the 944 * {@code ProtectionDomain} of the class. Any classes added to that 945 * package must contain the same set of certificates or a 946 * {@code SecurityException} will be thrown. Note that if 947 * {@code name} is {@code null}, this check is not performed. 948 * You should always pass in the <a href="#binary-name">binary name</a> of the 949 * class you are defining as well as the bytes. This ensures that the 950 * class you are defining is indeed the class you think it is. 951 * 952 * <p> If the specified {@code name} begins with "{@code java.}", it can 953 * only be defined by the {@linkplain #getPlatformClassLoader() 954 * platform class loader} or its ancestors; otherwise {@code SecurityException} 955 * will be thrown. If {@code name} is not {@code null}, it must be equal to 956 * the <a href="#binary-name">binary name</a> of the class 957 * specified by the byte array {@code b}, otherwise a {@link 958 * NoClassDefFoundError NoClassDefFoundError} will be thrown. 959 * 960 * <p> This method defines a package in this class loader corresponding to the 961 * package of the {@code Class} (if such a package has not already been defined 962 * in this class loader). The name of the defined package is derived from 963 * the <a href="#binary-name">binary name</a> of the class specified by 964 * the byte array {@code b}. 965 * Other properties of the defined package are as specified by {@link Package}. 966 * 967 * @param name 968 * The expected <a href="#binary-name">binary name</a> of the class, or 969 * {@code null} if not known 970 * 971 * @param b 972 * The bytes that make up the class data. The bytes in positions 973 * {@code off} through {@code off+len-1} should have the format 974 * of a valid class file as defined by 975 * <cite>The Java™ Virtual Machine Specification</cite>. 976 * 977 * @param off 978 * The start offset in {@code b} of the class data 979 * 980 * @param len 981 * The length of the class data 982 * 983 * @param protectionDomain 984 * The {@code ProtectionDomain} of the class 985 * 986 * @return The {@code Class} object created from the data, 987 * and {@code ProtectionDomain}. 988 * 989 * @throws ClassFormatError 990 * If the data did not contain a valid class 991 * 992 * @throws NoClassDefFoundError 993 * If {@code name} is not {@code null} and not equal to the 994 * <a href="#binary-name">binary name</a> of the class specified by {@code b} 995 * 996 * @throws IndexOutOfBoundsException 997 * If either {@code off} or {@code len} is negative, or if 998 * {@code off+len} is greater than {@code b.length}. 999 * 1000 * @throws SecurityException 1001 * If an attempt is made to add this class to a package that 1002 * contains classes that were signed by a different set of 1003 * certificates than this class, or if {@code name} begins with 1004 * "{@code java.}" and this class loader is not the platform 1005 * class loader or its ancestor. 1006 * 1007 * @revised 9 1008 * @spec JPMS 1009 */ 1010 protected final Class<?> defineClass(String name, byte[] b, int off, int len, 1011 ProtectionDomain protectionDomain) 1012 throws ClassFormatError 1013 { 1014 protectionDomain = preDefineClass(name, protectionDomain); 1015 String source = defineClassSourceLocation(protectionDomain); 1016 Class<?> c = defineClass1(this, name, b, off, len, protectionDomain, source); 1017 postDefineClass(c, protectionDomain); 1018 return c; 1019 } 1020 1021 /** 1022 * Converts a {@link java.nio.ByteBuffer ByteBuffer} into an instance 1023 * of class {@code Class}, with the given {@code ProtectionDomain}. 1024 * If the given {@code ProtectionDomain} is {@code null}, then a default 1025 * protection domain will be assigned to the class as 1026 * specified in the documentation for {@link #defineClass(String, byte[], 1027 * int, int)}. Before the class can be used it must be resolved. 1028 * 1029 * <p>The rules about the first class defined in a package determining the 1030 * set of certificates for the package, the restrictions on class names, 1031 * and the defined package of the class 1032 * are identical to those specified in the documentation for {@link 1033 * #defineClass(String, byte[], int, int, ProtectionDomain)}. 1034 * 1035 * <p> An invocation of this method of the form 1036 * <i>cl</i>{@code .defineClass(}<i>name</i>{@code ,} 1037 * <i>bBuffer</i>{@code ,} <i>pd</i>{@code )} yields exactly the same 1038 * result as the statements 1039 * 1040 *<p> <code> 1041 * ...<br> 1042 * byte[] temp = new byte[bBuffer.{@link 1043 * java.nio.ByteBuffer#remaining remaining}()];<br> 1044 * bBuffer.{@link java.nio.ByteBuffer#get(byte[]) 1045 * get}(temp);<br> 1046 * return {@link #defineClass(String, byte[], int, int, ProtectionDomain) 1047 * cl.defineClass}(name, temp, 0, 1048 * temp.length, pd);<br> 1049 * </code></p> 1050 * 1051 * @param name 1052 * The expected <a href="#binary-name">binary name</a>. of the class, or 1053 * {@code null} if not known 1054 * 1055 * @param b 1056 * The bytes that make up the class data. The bytes from positions 1057 * {@code b.position()} through {@code b.position() + b.limit() -1 1058 * } should have the format of a valid class file as defined by 1059 * <cite>The Java™ Virtual Machine Specification</cite>. 1060 * 1061 * @param protectionDomain 1062 * The {@code ProtectionDomain} of the class, or {@code null}. 1063 * 1064 * @return The {@code Class} object created from the data, 1065 * and {@code ProtectionDomain}. 1066 * 1067 * @throws ClassFormatError 1068 * If the data did not contain a valid class. 1069 * 1070 * @throws NoClassDefFoundError 1071 * If {@code name} is not {@code null} and not equal to the 1072 * <a href="#binary-name">binary name</a> of the class specified by {@code b} 1073 * 1074 * @throws SecurityException 1075 * If an attempt is made to add this class to a package that 1076 * contains classes that were signed by a different set of 1077 * certificates than this class, or if {@code name} begins with 1078 * "{@code java.}". 1079 * 1080 * @see #defineClass(String, byte[], int, int, ProtectionDomain) 1081 * 1082 * @since 1.5 1083 * @revised 9 1084 * @spec JPMS 1085 */ 1086 protected final Class<?> defineClass(String name, java.nio.ByteBuffer b, 1087 ProtectionDomain protectionDomain) 1088 throws ClassFormatError 1089 { 1090 int len = b.remaining(); 1091 1092 // Use byte[] if not a direct ByteBuffer: 1093 if (!b.isDirect()) { 1094 if (b.hasArray()) { 1095 return defineClass(name, b.array(), 1096 b.position() + b.arrayOffset(), len, 1097 protectionDomain); 1098 } else { 1099 // no array, or read-only array 1100 byte[] tb = new byte[len]; 1101 b.get(tb); // get bytes out of byte buffer. 1102 return defineClass(name, tb, 0, len, protectionDomain); 1103 } 1104 } 1105 1106 protectionDomain = preDefineClass(name, protectionDomain); 1107 String source = defineClassSourceLocation(protectionDomain); 1108 Class<?> c = defineClass2(this, name, b, b.position(), len, protectionDomain, source); 1109 postDefineClass(c, protectionDomain); 1110 return c; 1111 } 1112 1113 static native Class<?> defineClass1(ClassLoader loader, String name, byte[] b, int off, int len, 1114 ProtectionDomain pd, String source); 1115 1116 static native Class<?> defineClass2(ClassLoader loader, String name, java.nio.ByteBuffer b, 1117 int off, int len, ProtectionDomain pd, 1118 String source); 1119 1120 // true if the name is null or has the potential to be a valid binary name 1121 private boolean checkName(String name) { 1122 if ((name == null) || (name.isEmpty())) 1123 return true; 1124 if ((name.indexOf('/') != -1) || (name.charAt(0) == '[')) 1125 return false; 1126 return true; 1127 } 1128 1129 private void checkCerts(String name, CodeSource cs) { 1130 int i = name.lastIndexOf('.'); 1131 String pname = (i == -1) ? "" : name.substring(0, i); 1132 1133 Certificate[] certs = null; 1134 if (cs != null) { 1135 certs = cs.getCertificates(); 1136 } 1137 Certificate[] pcerts = null; 1138 if (parallelLockMap == null) { 1139 synchronized (this) { 1140 pcerts = package2certs.get(pname); 1141 if (pcerts == null) { 1142 package2certs.put(pname, (certs == null? nocerts:certs)); 1143 } 1144 } 1145 } else { 1146 pcerts = ((ConcurrentHashMap<String, Certificate[]>)package2certs). 1147 putIfAbsent(pname, (certs == null? nocerts:certs)); 1148 } 1149 if (pcerts != null && !compareCerts(pcerts, certs)) { 1150 throw new SecurityException("class \"" + name 1151 + "\"'s signer information does not match signer information" 1152 + " of other classes in the same package"); 1153 } 1154 } 1155 1156 /** 1157 * check to make sure the certs for the new class (certs) are the same as 1158 * the certs for the first class inserted in the package (pcerts) 1159 */ 1160 private boolean compareCerts(Certificate[] pcerts, 1161 Certificate[] certs) 1162 { 1163 // certs can be null, indicating no certs. 1164 if ((certs == null) || (certs.length == 0)) { 1165 return pcerts.length == 0; 1166 } 1167 1168 // the length must be the same at this point 1169 if (certs.length != pcerts.length) 1170 return false; 1171 1172 // go through and make sure all the certs in one array 1173 // are in the other and vice-versa. 1174 boolean match; 1175 for (Certificate cert : certs) { 1176 match = false; 1177 for (Certificate pcert : pcerts) { 1178 if (cert.equals(pcert)) { 1179 match = true; 1180 break; 1181 } 1182 } 1183 if (!match) return false; 1184 } 1185 1186 // now do the same for pcerts 1187 for (Certificate pcert : pcerts) { 1188 match = false; 1189 for (Certificate cert : certs) { 1190 if (pcert.equals(cert)) { 1191 match = true; 1192 break; 1193 } 1194 } 1195 if (!match) return false; 1196 } 1197 1198 return true; 1199 } 1200 1201 /** 1202 * Links the specified class. This (misleadingly named) method may be 1203 * used by a class loader to link a class. If the class {@code c} has 1204 * already been linked, then this method simply returns. Otherwise, the 1205 * class is linked as described in the "Execution" chapter of 1206 * <cite>The Java™ Language Specification</cite>. 1207 * 1208 * @param c 1209 * The class to link 1210 * 1211 * @throws NullPointerException 1212 * If {@code c} is {@code null}. 1213 * 1214 * @see #defineClass(String, byte[], int, int) 1215 */ 1216 protected final void resolveClass(Class<?> c) { 1217 if (c == null) { 1218 throw new NullPointerException(); 1219 } 1220 } 1221 1222 /** 1223 * Finds a class with the specified <a href="#binary-name">binary name</a>, 1224 * loading it if necessary. 1225 * 1226 * <p> This method loads the class through the system class loader (see 1227 * {@link #getSystemClassLoader()}). The {@code Class} object returned 1228 * might have more than one {@code ClassLoader} associated with it. 1229 * Subclasses of {@code ClassLoader} need not usually invoke this method, 1230 * because most class loaders need to override just {@link 1231 * #findClass(String)}. </p> 1232 * 1233 * @param name 1234 * The <a href="#binary-name">binary name</a> of the class 1235 * 1236 * @return The {@code Class} object for the specified {@code name} 1237 * 1238 * @throws ClassNotFoundException 1239 * If the class could not be found 1240 * 1241 * @see #ClassLoader(ClassLoader) 1242 * @see #getParent() 1243 */ 1244 protected final Class<?> findSystemClass(String name) 1245 throws ClassNotFoundException 1246 { 1247 return getSystemClassLoader().loadClass(name); 1248 } 1249 1250 /** 1251 * Returns a class loaded by the bootstrap class loader; 1252 * or return null if not found. 1253 */ 1254 Class<?> findBootstrapClassOrNull(String name) { 1255 if (!checkName(name)) return null; 1256 1257 return findBootstrapClass(name); 1258 } 1259 1260 // return null if not found 1261 private native Class<?> findBootstrapClass(String name); 1262 1263 /** 1264 * Returns the class with the given <a href="#binary-name">binary name</a> if this 1265 * loader has been recorded by the Java virtual machine as an initiating 1266 * loader of a class with that <a href="#binary-name">binary name</a>. Otherwise 1267 * {@code null} is returned. 1268 * 1269 * @param name 1270 * The <a href="#binary-name">binary name</a> of the class 1271 * 1272 * @return The {@code Class} object, or {@code null} if the class has 1273 * not been loaded 1274 * 1275 * @since 1.1 1276 */ 1277 protected final Class<?> findLoadedClass(String name) { 1278 if (!checkName(name)) 1279 return null; 1280 return findLoadedClass0(name); 1281 } 1282 1283 private final native Class<?> findLoadedClass0(String name); 1284 1285 /** 1286 * Sets the signers of a class. This should be invoked after defining a 1287 * class. 1288 * 1289 * @param c 1290 * The {@code Class} object 1291 * 1292 * @param signers 1293 * The signers for the class 1294 * 1295 * @since 1.1 1296 */ 1297 protected final void setSigners(Class<?> c, Object[] signers) { 1298 c.setSigners(signers); 1299 } 1300 1301 1302 // -- Resources -- 1303 1304 /** 1305 * Returns a URL to a resource in a module defined to this class loader. 1306 * Class loader implementations that support loading from modules 1307 * should override this method. 1308 * 1309 * @apiNote This method is the basis for the {@link 1310 * Class#getResource Class.getResource}, {@link Class#getResourceAsStream 1311 * Class.getResourceAsStream}, and {@link Module#getResourceAsStream 1312 * Module.getResourceAsStream} methods. It is not subject to the rules for 1313 * encapsulation specified by {@code Module.getResourceAsStream}. 1314 * 1315 * @implSpec The default implementation attempts to find the resource by 1316 * invoking {@link #findResource(String)} when the {@code moduleName} is 1317 * {@code null}. It otherwise returns {@code null}. 1318 * 1319 * @param moduleName 1320 * The module name; or {@code null} to find a resource in the 1321 * {@linkplain #getUnnamedModule() unnamed module} for this 1322 * class loader 1323 * @param name 1324 * The resource name 1325 * 1326 * @return A URL to the resource; {@code null} if the resource could not be 1327 * found, a URL could not be constructed to locate the resource, 1328 * access to the resource is denied by the security manager, or 1329 * there isn't a module of the given name defined to the class 1330 * loader. 1331 * 1332 * @throws IOException 1333 * If I/O errors occur 1334 * 1335 * @see java.lang.module.ModuleReader#find(String) 1336 * @since 9 1337 * @spec JPMS 1338 */ 1339 protected URL findResource(String moduleName, String name) throws IOException { 1340 if (moduleName == null) { 1341 return findResource(name); 1342 } else { 1343 return null; 1344 } 1345 } 1346 1347 /** 1348 * Finds the resource with the given name. A resource is some data 1349 * (images, audio, text, etc) that can be accessed by class code in a way 1350 * that is independent of the location of the code. 1351 * 1352 * <p> The name of a resource is a '{@code /}'-separated path name that 1353 * identifies the resource. </p> 1354 * 1355 * <p> Resources in named modules are subject to the encapsulation rules 1356 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. 1357 * Additionally, and except for the special case where the resource has a 1358 * name ending with "{@code .class}", this method will only find resources in 1359 * packages of named modules when the package is {@link Module#isOpen(String) 1360 * opened} unconditionally (even if the caller of this method is in the 1361 * same module as the resource). </p> 1362 * 1363 * @implSpec The default implementation will first search the parent class 1364 * loader for the resource; if the parent is {@code null} the path of the 1365 * class loader built into the virtual machine is searched. If not found, 1366 * this method will invoke {@link #findResource(String)} to find the resource. 1367 * 1368 * @apiNote Where several modules are defined to the same class loader, 1369 * and where more than one module contains a resource with the given name, 1370 * then the ordering that modules are searched is not specified and may be 1371 * very unpredictable. 1372 * When overriding this method it is recommended that an implementation 1373 * ensures that any delegation is consistent with the {@link 1374 * #getResources(java.lang.String) getResources(String)} method. 1375 * 1376 * @param name 1377 * The resource name 1378 * 1379 * @return {@code URL} object for reading the resource; {@code null} if 1380 * the resource could not be found, a {@code URL} could not be 1381 * constructed to locate the resource, the resource is in a package 1382 * that is not opened unconditionally, or access to the resource is 1383 * denied by the security manager. 1384 * 1385 * @throws NullPointerException If {@code name} is {@code null} 1386 * 1387 * @since 1.1 1388 * @revised 9 1389 * @spec JPMS 1390 */ 1391 public URL getResource(String name) { 1392 Objects.requireNonNull(name); 1393 URL url; 1394 if (parent != null) { 1395 url = parent.getResource(name); 1396 } else { 1397 url = BootLoader.findResource(name); 1398 } 1399 if (url == null) { 1400 url = findResource(name); 1401 } 1402 return url; 1403 } 1404 1405 /** 1406 * Finds all the resources with the given name. A resource is some data 1407 * (images, audio, text, etc) that can be accessed by class code in a way 1408 * that is independent of the location of the code. 1409 * 1410 * <p> The name of a resource is a {@code /}-separated path name that 1411 * identifies the resource. </p> 1412 * 1413 * <p> Resources in named modules are subject to the encapsulation rules 1414 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. 1415 * Additionally, and except for the special case where the resource has a 1416 * name ending with "{@code .class}", this method will only find resources in 1417 * packages of named modules when the package is {@link Module#isOpen(String) 1418 * opened} unconditionally (even if the caller of this method is in the 1419 * same module as the resource). </p> 1420 * 1421 * @implSpec The default implementation will first search the parent class 1422 * loader for the resource; if the parent is {@code null} the path of the 1423 * class loader built into the virtual machine is searched. It then 1424 * invokes {@link #findResources(String)} to find the resources with the 1425 * name in this class loader. It returns an enumeration whose elements 1426 * are the URLs found by searching the parent class loader followed by 1427 * the elements found with {@code findResources}. 1428 * 1429 * @apiNote Where several modules are defined to the same class loader, 1430 * and where more than one module contains a resource with the given name, 1431 * then the ordering is not specified and may be very unpredictable. 1432 * When overriding this method it is recommended that an 1433 * implementation ensures that any delegation is consistent with the {@link 1434 * #getResource(java.lang.String) getResource(String)} method. This should 1435 * ensure that the first element returned by the Enumeration's 1436 * {@code nextElement} method is the same resource that the 1437 * {@code getResource(String)} method would return. 1438 * 1439 * @param name 1440 * The resource name 1441 * 1442 * @return An enumeration of {@link java.net.URL URL} objects for the 1443 * resource. If no resources could be found, the enumeration will 1444 * be empty. Resources for which a {@code URL} cannot be 1445 * constructed, are in a package that is not opened 1446 * unconditionally, or access to the resource is denied by the 1447 * security manager, are not returned in the enumeration. 1448 * 1449 * @throws IOException 1450 * If I/O errors occur 1451 * @throws NullPointerException If {@code name} is {@code null} 1452 * 1453 * @since 1.2 1454 * @revised 9 1455 * @spec JPMS 1456 */ 1457 public Enumeration<URL> getResources(String name) throws IOException { 1458 Objects.requireNonNull(name); 1459 @SuppressWarnings("unchecked") 1460 Enumeration<URL>[] tmp = (Enumeration<URL>[]) new Enumeration<?>[2]; 1461 if (parent != null) { 1462 tmp[0] = parent.getResources(name); 1463 } else { 1464 tmp[0] = BootLoader.findResources(name); 1465 } 1466 tmp[1] = findResources(name); 1467 1468 return new CompoundEnumeration<>(tmp); 1469 } 1470 1471 /** 1472 * Returns a stream whose elements are the URLs of all the resources with 1473 * the given name. A resource is some data (images, audio, text, etc) that 1474 * can be accessed by class code in a way that is independent of the 1475 * location of the code. 1476 * 1477 * <p> The name of a resource is a {@code /}-separated path name that 1478 * identifies the resource. 1479 * 1480 * <p> The resources will be located when the returned stream is evaluated. 1481 * If the evaluation results in an {@code IOException} then the I/O 1482 * exception is wrapped in an {@link UncheckedIOException} that is then 1483 * thrown. 1484 * 1485 * <p> Resources in named modules are subject to the encapsulation rules 1486 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. 1487 * Additionally, and except for the special case where the resource has a 1488 * name ending with "{@code .class}", this method will only find resources in 1489 * packages of named modules when the package is {@link Module#isOpen(String) 1490 * opened} unconditionally (even if the caller of this method is in the 1491 * same module as the resource). </p> 1492 * 1493 * @implSpec The default implementation invokes {@link #getResources(String) 1494 * getResources} to find all the resources with the given name and returns 1495 * a stream with the elements in the enumeration as the source. 1496 * 1497 * @apiNote When overriding this method it is recommended that an 1498 * implementation ensures that any delegation is consistent with the {@link 1499 * #getResource(java.lang.String) getResource(String)} method. This should 1500 * ensure that the first element returned by the stream is the same 1501 * resource that the {@code getResource(String)} method would return. 1502 * 1503 * @param name 1504 * The resource name 1505 * 1506 * @return A stream of resource {@link java.net.URL URL} objects. If no 1507 * resources could be found, the stream will be empty. Resources 1508 * for which a {@code URL} cannot be constructed, are in a package 1509 * that is not opened unconditionally, or access to the resource 1510 * is denied by the security manager, will not be in the stream. 1511 * 1512 * @throws NullPointerException If {@code name} is {@code null} 1513 * 1514 * @since 9 1515 */ 1516 public Stream<URL> resources(String name) { 1517 Objects.requireNonNull(name); 1518 int characteristics = Spliterator.NONNULL | Spliterator.IMMUTABLE; 1519 Supplier<Spliterator<URL>> si = () -> { 1520 try { 1521 return Spliterators.spliteratorUnknownSize( 1522 getResources(name).asIterator(), characteristics); 1523 } catch (IOException e) { 1524 throw new UncheckedIOException(e); 1525 } 1526 }; 1527 return StreamSupport.stream(si, characteristics, false); 1528 } 1529 1530 /** 1531 * Finds the resource with the given name. Class loader implementations 1532 * should override this method. 1533 * 1534 * <p> For resources in named modules then the method must implement the 1535 * rules for encapsulation specified in the {@code Module} {@link 1536 * Module#getResourceAsStream getResourceAsStream} method. Additionally, 1537 * it must not find non-"{@code .class}" resources in packages of named 1538 * modules unless the package is {@link Module#isOpen(String) opened} 1539 * unconditionally. </p> 1540 * 1541 * @implSpec The default implementation returns {@code null}. 1542 * 1543 * @param name 1544 * The resource name 1545 * 1546 * @return {@code URL} object for reading the resource; {@code null} if 1547 * the resource could not be found, a {@code URL} could not be 1548 * constructed to locate the resource, the resource is in a package 1549 * that is not opened unconditionally, or access to the resource is 1550 * denied by the security manager. 1551 * 1552 * @since 1.2 1553 * @revised 9 1554 * @spec JPMS 1555 */ 1556 protected URL findResource(String name) { 1557 return null; 1558 } 1559 1560 /** 1561 * Returns an enumeration of {@link java.net.URL URL} objects 1562 * representing all the resources with the given name. Class loader 1563 * implementations should override this method. 1564 * 1565 * <p> For resources in named modules then the method must implement the 1566 * rules for encapsulation specified in the {@code Module} {@link 1567 * Module#getResourceAsStream getResourceAsStream} method. Additionally, 1568 * it must not find non-"{@code .class}" resources in packages of named 1569 * modules unless the package is {@link Module#isOpen(String) opened} 1570 * unconditionally. </p> 1571 * 1572 * @implSpec The default implementation returns an enumeration that 1573 * contains no elements. 1574 * 1575 * @param name 1576 * The resource name 1577 * 1578 * @return An enumeration of {@link java.net.URL URL} objects for 1579 * the resource. If no resources could be found, the enumeration 1580 * will be empty. Resources for which a {@code URL} cannot be 1581 * constructed, are in a package that is not opened unconditionally, 1582 * or access to the resource is denied by the security manager, 1583 * are not returned in the enumeration. 1584 * 1585 * @throws IOException 1586 * If I/O errors occur 1587 * 1588 * @since 1.2 1589 * @revised 9 1590 * @spec JPMS 1591 */ 1592 protected Enumeration<URL> findResources(String name) throws IOException { 1593 return Collections.emptyEnumeration(); 1594 } 1595 1596 /** 1597 * Registers the caller as 1598 * {@linkplain #isRegisteredAsParallelCapable() parallel capable}. 1599 * The registration succeeds if and only if all of the following 1600 * conditions are met: 1601 * <ol> 1602 * <li> no instance of the caller has been created</li> 1603 * <li> all of the super classes (except class Object) of the caller are 1604 * registered as parallel capable</li> 1605 * </ol> 1606 * <p>Note that once a class loader is registered as parallel capable, there 1607 * is no way to change it back.</p> 1608 * 1609 * @return {@code true} if the caller is successfully registered as 1610 * parallel capable and {@code false} if otherwise. 1611 * 1612 * @see #isRegisteredAsParallelCapable() 1613 * 1614 * @since 1.7 1615 */ 1616 @CallerSensitive 1617 protected static boolean registerAsParallelCapable() { 1618 Class<? extends ClassLoader> callerClass = 1619 Reflection.getCallerClass().asSubclass(ClassLoader.class); 1620 return ParallelLoaders.register(callerClass); 1621 } 1622 1623 /** 1624 * Returns {@code true} if this class loader is registered as 1625 * {@linkplain #registerAsParallelCapable parallel capable}, otherwise 1626 * {@code false}. 1627 * 1628 * @return {@code true} if this class loader is parallel capable, 1629 * otherwise {@code false}. 1630 * 1631 * @see #registerAsParallelCapable() 1632 * 1633 * @since 9 1634 */ 1635 public final boolean isRegisteredAsParallelCapable() { 1636 return ParallelLoaders.isRegistered(this.getClass()); 1637 } 1638 1639 /** 1640 * Find a resource of the specified name from the search path used to load 1641 * classes. This method locates the resource through the system class 1642 * loader (see {@link #getSystemClassLoader()}). 1643 * 1644 * <p> Resources in named modules are subject to the encapsulation rules 1645 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. 1646 * Additionally, and except for the special case where the resource has a 1647 * name ending with "{@code .class}", this method will only find resources in 1648 * packages of named modules when the package is {@link Module#isOpen(String) 1649 * opened} unconditionally. </p> 1650 * 1651 * @param name 1652 * The resource name 1653 * 1654 * @return A {@link java.net.URL URL} to the resource; {@code 1655 * null} if the resource could not be found, a URL could not be 1656 * constructed to locate the resource, the resource is in a package 1657 * that is not opened unconditionally or access to the resource is 1658 * denied by the security manager. 1659 * 1660 * @since 1.1 1661 * @revised 9 1662 * @spec JPMS 1663 */ 1664 public static URL getSystemResource(String name) { 1665 return getSystemClassLoader().getResource(name); 1666 } 1667 1668 /** 1669 * Finds all resources of the specified name from the search path used to 1670 * load classes. The resources thus found are returned as an 1671 * {@link java.util.Enumeration Enumeration} of {@link 1672 * java.net.URL URL} objects. 1673 * 1674 * <p> The search order is described in the documentation for {@link 1675 * #getSystemResource(String)}. </p> 1676 * 1677 * <p> Resources in named modules are subject to the encapsulation rules 1678 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. 1679 * Additionally, and except for the special case where the resource has a 1680 * name ending with "{@code .class}", this method will only find resources in 1681 * packages of named modules when the package is {@link Module#isOpen(String) 1682 * opened} unconditionally. </p> 1683 * 1684 * @param name 1685 * The resource name 1686 * 1687 * @return An enumeration of {@link java.net.URL URL} objects for 1688 * the resource. If no resources could be found, the enumeration 1689 * will be empty. Resources for which a {@code URL} cannot be 1690 * constructed, are in a package that is not opened unconditionally, 1691 * or access to the resource is denied by the security manager, 1692 * are not returned in the enumeration. 1693 * 1694 * @throws IOException 1695 * If I/O errors occur 1696 * 1697 * @since 1.2 1698 * @revised 9 1699 * @spec JPMS 1700 */ 1701 public static Enumeration<URL> getSystemResources(String name) 1702 throws IOException 1703 { 1704 return getSystemClassLoader().getResources(name); 1705 } 1706 1707 /** 1708 * Returns an input stream for reading the specified resource. 1709 * 1710 * <p> The search order is described in the documentation for {@link 1711 * #getResource(String)}. </p> 1712 * 1713 * <p> Resources in named modules are subject to the encapsulation rules 1714 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. 1715 * Additionally, and except for the special case where the resource has a 1716 * name ending with "{@code .class}", this method will only find resources in 1717 * packages of named modules when the package is {@link Module#isOpen(String) 1718 * opened} unconditionally. </p> 1719 * 1720 * @param name 1721 * The resource name 1722 * 1723 * @return An input stream for reading the resource; {@code null} if the 1724 * resource could not be found, the resource is in a package that 1725 * is not opened unconditionally, or access to the resource is 1726 * denied by the security manager. 1727 * 1728 * @throws NullPointerException If {@code name} is {@code null} 1729 * 1730 * @since 1.1 1731 * @revised 9 1732 * @spec JPMS 1733 */ 1734 public InputStream getResourceAsStream(String name) { 1735 Objects.requireNonNull(name); 1736 URL url = getResource(name); 1737 try { 1738 return url != null ? url.openStream() : null; 1739 } catch (IOException e) { 1740 return null; 1741 } 1742 } 1743 1744 /** 1745 * Open for reading, a resource of the specified name from the search path 1746 * used to load classes. This method locates the resource through the 1747 * system class loader (see {@link #getSystemClassLoader()}). 1748 * 1749 * <p> Resources in named modules are subject to the encapsulation rules 1750 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. 1751 * Additionally, and except for the special case where the resource has a 1752 * name ending with "{@code .class}", this method will only find resources in 1753 * packages of named modules when the package is {@link Module#isOpen(String) 1754 * opened} unconditionally. </p> 1755 * 1756 * @param name 1757 * The resource name 1758 * 1759 * @return An input stream for reading the resource; {@code null} if the 1760 * resource could not be found, the resource is in a package that 1761 * is not opened unconditionally, or access to the resource is 1762 * denied by the security manager. 1763 * 1764 * @since 1.1 1765 * @revised 9 1766 * @spec JPMS 1767 */ 1768 public static InputStream getSystemResourceAsStream(String name) { 1769 URL url = getSystemResource(name); 1770 try { 1771 return url != null ? url.openStream() : null; 1772 } catch (IOException e) { 1773 return null; 1774 } 1775 } 1776 1777 1778 // -- Hierarchy -- 1779 1780 /** 1781 * Returns the parent class loader for delegation. Some implementations may 1782 * use {@code null} to represent the bootstrap class loader. This method 1783 * will return {@code null} in such implementations if this class loader's 1784 * parent is the bootstrap class loader. 1785 * 1786 * @return The parent {@code ClassLoader} 1787 * 1788 * @throws SecurityException 1789 * If a security manager is present, and the caller's class loader 1790 * is not {@code null} and is not an ancestor of this class loader, 1791 * and the caller does not have the 1792 * {@link RuntimePermission}{@code ("getClassLoader")} 1793 * 1794 * @since 1.2 1795 */ 1796 @CallerSensitive 1797 public final ClassLoader getParent() { 1798 if (parent == null) 1799 return null; 1800 SecurityManager sm = System.getSecurityManager(); 1801 if (sm != null) { 1802 // Check access to the parent class loader 1803 // If the caller's class loader is same as this class loader, 1804 // permission check is performed. 1805 checkClassLoaderPermission(parent, Reflection.getCallerClass()); 1806 } 1807 return parent; 1808 } 1809 1810 /** 1811 * Returns the unnamed {@code Module} for this class loader. 1812 * 1813 * @return The unnamed Module for this class loader 1814 * 1815 * @see Module#isNamed() 1816 * @since 9 1817 * @spec JPMS 1818 */ 1819 public final Module getUnnamedModule() { 1820 return unnamedModule; 1821 } 1822 1823 /** 1824 * Returns the platform class loader. All 1825 * <a href="#builtinLoaders">platform classes</a> are visible to 1826 * the platform class loader. 1827 * 1828 * @implNote The name of the builtin platform class loader is 1829 * {@code "platform"}. 1830 * 1831 * @return The platform {@code ClassLoader}. 1832 * 1833 * @throws SecurityException 1834 * If a security manager is present, and the caller's class loader is 1835 * not {@code null}, and the caller's class loader is not the same 1836 * as or an ancestor of the platform class loader, 1837 * and the caller does not have the 1838 * {@link RuntimePermission}{@code ("getClassLoader")} 1839 * 1840 * @since 9 1841 * @spec JPMS 1842 */ 1843 @CallerSensitive 1844 public static ClassLoader getPlatformClassLoader() { 1845 SecurityManager sm = System.getSecurityManager(); 1846 ClassLoader loader = getBuiltinPlatformClassLoader(); 1847 if (sm != null) { 1848 checkClassLoaderPermission(loader, Reflection.getCallerClass()); 1849 } 1850 return loader; 1851 } 1852 1853 /** 1854 * Returns the system class loader. This is the default 1855 * delegation parent for new {@code ClassLoader} instances, and is 1856 * typically the class loader used to start the application. 1857 * 1858 * <p> This method is first invoked early in the runtime's startup 1859 * sequence, at which point it creates the system class loader. This 1860 * class loader will be the context class loader for the main application 1861 * thread (for example, the thread that invokes the {@code main} method of 1862 * the main class). 1863 * 1864 * <p> The default system class loader is an implementation-dependent 1865 * instance of this class. 1866 * 1867 * <p> If the system property "{@systemProperty java.system.class.loader}" 1868 * is defined when this method is first invoked then the value of that 1869 * property is taken to be the name of a class that will be returned as the 1870 * system class loader. The class is loaded using the default system class 1871 * loader and must define a public constructor that takes a single parameter 1872 * of type {@code ClassLoader} which is used as the delegation parent. An 1873 * instance is then created using this constructor with the default system 1874 * class loader as the parameter. The resulting class loader is defined 1875 * to be the system class loader. During construction, the class loader 1876 * should take great care to avoid calling {@code getSystemClassLoader()}. 1877 * If circular initialization of the system class loader is detected then 1878 * an {@code IllegalStateException} is thrown. 1879 * 1880 * @implNote The system property to override the system class loader is not 1881 * examined until the VM is almost fully initialized. Code that executes 1882 * this method during startup should take care not to cache the return 1883 * value until the system is fully initialized. 1884 * 1885 * <p> The name of the built-in system class loader is {@code "app"}. 1886 * The system property "{@code java.class.path}" is read during early 1887 * initialization of the VM to determine the class path. 1888 * An empty value of "{@code java.class.path}" property is interpreted 1889 * differently depending on whether the initial module (the module 1890 * containing the main class) is named or unnamed: 1891 * If named, the built-in system class loader will have no class path and 1892 * will search for classes and resources using the application module path; 1893 * otherwise, if unnamed, it will set the class path to the current 1894 * working directory. 1895 * 1896 * <p> JAR files on the class path may contain a {@code Class-Path} manifest 1897 * attribute to specify dependent JAR files to be included in the class path. 1898 * {@code Class-Path} entries must meet certain conditions for validity (see 1899 * the <a href="{@docRoot}/../specs/jar/jar.html#class-path-attribute"> 1900 * JAR File Specification</a> for details). Invalid {@code Class-Path} 1901 * entries are ignored. For debugging purposes, ignored entries can be 1902 * printed to the console if the 1903 * {@systemProperty jdk.net.URLClassPath.showIgnoredClassPathEntries} system 1904 * property is set to {@code true}. 1905 * 1906 * @return The system {@code ClassLoader} 1907 * 1908 * @throws SecurityException 1909 * If a security manager is present, and the caller's class loader 1910 * is not {@code null} and is not the same as or an ancestor of the 1911 * system class loader, and the caller does not have the 1912 * {@link RuntimePermission}{@code ("getClassLoader")} 1913 * 1914 * @throws IllegalStateException 1915 * If invoked recursively during the construction of the class 1916 * loader specified by the "{@code java.system.class.loader}" 1917 * property. 1918 * 1919 * @throws Error 1920 * If the system property "{@code java.system.class.loader}" 1921 * is defined but the named class could not be loaded, the 1922 * provider class does not define the required constructor, or an 1923 * exception is thrown by that constructor when it is invoked. The 1924 * underlying cause of the error can be retrieved via the 1925 * {@link Throwable#getCause()} method. 1926 * 1927 * @revised 1.4 1928 * @revised 9 1929 * @spec JPMS 1930 */ 1931 @CallerSensitive 1932 public static ClassLoader getSystemClassLoader() { 1933 switch (VM.initLevel()) { 1934 case 0: 1935 case 1: 1936 case 2: 1937 // the system class loader is the built-in app class loader during startup 1938 return getBuiltinAppClassLoader(); 1939 case 3: 1940 String msg = "getSystemClassLoader cannot be called during the system class loader instantiation"; 1941 throw new IllegalStateException(msg); 1942 default: 1943 // system fully initialized 1944 assert VM.isBooted() && scl != null; 1945 SecurityManager sm = System.getSecurityManager(); 1946 if (sm != null) { 1947 checkClassLoaderPermission(scl, Reflection.getCallerClass()); 1948 } 1949 return scl; 1950 } 1951 } 1952 1953 static ClassLoader getBuiltinPlatformClassLoader() { 1954 return ClassLoaders.platformClassLoader(); 1955 } 1956 1957 static ClassLoader getBuiltinAppClassLoader() { 1958 return ClassLoaders.appClassLoader(); 1959 } 1960 1961 /* 1962 * Initialize the system class loader that may be a custom class on the 1963 * application class path or application module path. 1964 * 1965 * @see java.lang.System#initPhase3 1966 */ 1967 static synchronized ClassLoader initSystemClassLoader() { 1968 if (VM.initLevel() != 3) { 1969 throw new InternalError("system class loader cannot be set at initLevel " + 1970 VM.initLevel()); 1971 } 1972 1973 // detect recursive initialization 1974 if (scl != null) { 1975 throw new IllegalStateException("recursive invocation"); 1976 } 1977 1978 ClassLoader builtinLoader = getBuiltinAppClassLoader(); 1979 1980 // All are privileged frames. No need to call doPrivileged. 1981 String cn = System.getProperty("java.system.class.loader"); 1982 if (cn != null) { 1983 try { 1984 // custom class loader is only supported to be loaded from unnamed module 1985 Constructor<?> ctor = Class.forName(cn, false, builtinLoader) 1986 .getDeclaredConstructor(ClassLoader.class); 1987 scl = (ClassLoader) ctor.newInstance(builtinLoader); 1988 } catch (Exception e) { 1989 Throwable cause = e; 1990 if (e instanceof InvocationTargetException) { 1991 cause = e.getCause(); 1992 if (cause instanceof Error) { 1993 throw (Error) cause; 1994 } 1995 } 1996 if (cause instanceof RuntimeException) { 1997 throw (RuntimeException) cause; 1998 } 1999 throw new Error(cause.getMessage(), cause); 2000 } 2001 } else { 2002 scl = builtinLoader; 2003 } 2004 return scl; 2005 } 2006 2007 // Returns true if the specified class loader can be found in this class 2008 // loader's delegation chain. 2009 boolean isAncestor(ClassLoader cl) { 2010 ClassLoader acl = this; 2011 do { 2012 acl = acl.parent; 2013 if (cl == acl) { 2014 return true; 2015 } 2016 } while (acl != null); 2017 return false; 2018 } 2019 2020 // Tests if class loader access requires "getClassLoader" permission 2021 // check. A class loader 'from' can access class loader 'to' if 2022 // class loader 'from' is same as class loader 'to' or an ancestor 2023 // of 'to'. The class loader in a system domain can access 2024 // any class loader. 2025 private static boolean needsClassLoaderPermissionCheck(ClassLoader from, 2026 ClassLoader to) 2027 { 2028 if (from == to) 2029 return false; 2030 2031 if (from == null) 2032 return false; 2033 2034 return !to.isAncestor(from); 2035 } 2036 2037 // Returns the class's class loader, or null if none. 2038 static ClassLoader getClassLoader(Class<?> caller) { 2039 // This can be null if the VM is requesting it 2040 if (caller == null) { 2041 return null; 2042 } 2043 // Circumvent security check since this is package-private 2044 return caller.getClassLoader0(); 2045 } 2046 2047 /* 2048 * Checks RuntimePermission("getClassLoader") permission 2049 * if caller's class loader is not null and caller's class loader 2050 * is not the same as or an ancestor of the given cl argument. 2051 */ 2052 static void checkClassLoaderPermission(ClassLoader cl, Class<?> caller) { 2053 SecurityManager sm = System.getSecurityManager(); 2054 if (sm != null) { 2055 // caller can be null if the VM is requesting it 2056 ClassLoader ccl = getClassLoader(caller); 2057 if (needsClassLoaderPermissionCheck(ccl, cl)) { 2058 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION); 2059 } 2060 } 2061 } 2062 2063 // The system class loader 2064 // @GuardedBy("ClassLoader.class") 2065 private static volatile ClassLoader scl; 2066 2067 // -- Package -- 2068 2069 /** 2070 * Define a Package of the given Class object. 2071 * 2072 * If the given class represents an array type, a primitive type or void, 2073 * this method returns {@code null}. 2074 * 2075 * This method does not throw IllegalArgumentException. 2076 */ 2077 Package definePackage(Class<?> c) { 2078 if (c.isPrimitive() || c.isArray()) { 2079 return null; 2080 } 2081 2082 return definePackage(c.getPackageName(), c.getModule()); 2083 } 2084 2085 /** 2086 * Defines a Package of the given name and module 2087 * 2088 * This method does not throw IllegalArgumentException. 2089 * 2090 * @param name package name 2091 * @param m module 2092 */ 2093 Package definePackage(String name, Module m) { 2094 if (name.isEmpty() && m.isNamed()) { 2095 throw new InternalError("unnamed package in " + m); 2096 } 2097 2098 // check if Package object is already defined 2099 NamedPackage pkg = packages.get(name); 2100 if (pkg instanceof Package) 2101 return (Package)pkg; 2102 2103 return (Package)packages.compute(name, (n, p) -> toPackage(n, p, m)); 2104 } 2105 2106 /* 2107 * Returns a Package object for the named package 2108 */ 2109 private Package toPackage(String name, NamedPackage p, Module m) { 2110 // define Package object if the named package is not yet defined 2111 if (p == null) 2112 return NamedPackage.toPackage(name, m); 2113 2114 // otherwise, replace the NamedPackage object with Package object 2115 if (p instanceof Package) 2116 return (Package)p; 2117 2118 return NamedPackage.toPackage(p.packageName(), p.module()); 2119 } 2120 2121 /** 2122 * Defines a package by <a href="#binary-name">name</a> in this {@code ClassLoader}. 2123 * <p> 2124 * <a href="#binary-name">Package names</a> must be unique within a class loader and 2125 * cannot be redefined or changed once created. 2126 * <p> 2127 * If a class loader wishes to define a package with specific properties, 2128 * such as version information, then the class loader should call this 2129 * {@code definePackage} method before calling {@code defineClass}. 2130 * Otherwise, the 2131 * {@link #defineClass(String, byte[], int, int, ProtectionDomain) defineClass} 2132 * method will define a package in this class loader corresponding to the package 2133 * of the newly defined class; the properties of this defined package are 2134 * specified by {@link Package}. 2135 * 2136 * @apiNote 2137 * A class loader that wishes to define a package for classes in a JAR 2138 * typically uses the specification and implementation titles, versions, and 2139 * vendors from the JAR's manifest. If the package is specified as 2140 * {@linkplain java.util.jar.Attributes.Name#SEALED sealed} in the JAR's manifest, 2141 * the {@code URL} of the JAR file is typically used as the {@code sealBase}. 2142 * If classes of package {@code 'p'} defined by this class loader 2143 * are loaded from multiple JARs, the {@code Package} object may contain 2144 * different information depending on the first class of package {@code 'p'} 2145 * defined and which JAR's manifest is read first to explicitly define 2146 * package {@code 'p'}. 2147 * 2148 * <p> It is strongly recommended that a class loader does not call this 2149 * method to explicitly define packages in <em>named modules</em>; instead, 2150 * the package will be automatically defined when a class is {@linkplain 2151 * #defineClass(String, byte[], int, int, ProtectionDomain) being defined}. 2152 * If it is desirable to define {@code Package} explicitly, it should ensure 2153 * that all packages in a named module are defined with the properties 2154 * specified by {@link Package}. Otherwise, some {@code Package} objects 2155 * in a named module may be for example sealed with different seal base. 2156 * 2157 * @param name 2158 * The <a href="#binary-name">package name</a> 2159 * 2160 * @param specTitle 2161 * The specification title 2162 * 2163 * @param specVersion 2164 * The specification version 2165 * 2166 * @param specVendor 2167 * The specification vendor 2168 * 2169 * @param implTitle 2170 * The implementation title 2171 * 2172 * @param implVersion 2173 * The implementation version 2174 * 2175 * @param implVendor 2176 * The implementation vendor 2177 * 2178 * @param sealBase 2179 * If not {@code null}, then this package is sealed with 2180 * respect to the given code source {@link java.net.URL URL} 2181 * object. Otherwise, the package is not sealed. 2182 * 2183 * @return The newly defined {@code Package} object 2184 * 2185 * @throws NullPointerException 2186 * if {@code name} is {@code null}. 2187 * 2188 * @throws IllegalArgumentException 2189 * if a package of the given {@code name} is already 2190 * defined by this class loader 2191 * 2192 * 2193 * @since 1.2 2194 * @revised 9 2195 * @spec JPMS 2196 * 2197 * @jvms 5.3 Creation and Loading 2198 * @see <a href="{@docRoot}/../specs/jar/jar.html#package-sealing"> 2199 * The JAR File Specification: Package Sealing</a> 2200 */ 2201 protected Package definePackage(String name, String specTitle, 2202 String specVersion, String specVendor, 2203 String implTitle, String implVersion, 2204 String implVendor, URL sealBase) 2205 { 2206 Objects.requireNonNull(name); 2207 2208 // definePackage is not final and may be overridden by custom class loader 2209 Package p = new Package(name, specTitle, specVersion, specVendor, 2210 implTitle, implVersion, implVendor, 2211 sealBase, this); 2212 2213 if (packages.putIfAbsent(name, p) != null) 2214 throw new IllegalArgumentException(name); 2215 2216 return p; 2217 } 2218 2219 /** 2220 * Returns a {@code Package} of the given <a href="#binary-name">name</a> that 2221 * has been defined by this class loader. 2222 * 2223 * @param name The <a href="#binary-name">package name</a> 2224 * 2225 * @return The {@code Package} of the given name that has been defined 2226 * by this class loader, or {@code null} if not found 2227 * 2228 * @throws NullPointerException 2229 * if {@code name} is {@code null}. 2230 * 2231 * @jvms 5.3 Creation and Loading 2232 * 2233 * @since 9 2234 * @spec JPMS 2235 */ 2236 public final Package getDefinedPackage(String name) { 2237 Objects.requireNonNull(name, "name cannot be null"); 2238 2239 NamedPackage p = packages.get(name); 2240 if (p == null) 2241 return null; 2242 2243 return definePackage(name, p.module()); 2244 } 2245 2246 /** 2247 * Returns all of the {@code Package}s that have been defined by 2248 * this class loader. The returned array has no duplicated {@code Package}s 2249 * of the same name. 2250 * 2251 * @apiNote This method returns an array rather than a {@code Set} or {@code Stream} 2252 * for consistency with the existing {@link #getPackages} method. 2253 * 2254 * @return The array of {@code Package} objects that have been defined by 2255 * this class loader; or an zero length array if no package has been 2256 * defined by this class loader. 2257 * 2258 * @jvms 5.3 Creation and Loading 2259 * 2260 * @since 9 2261 * @spec JPMS 2262 */ 2263 public final Package[] getDefinedPackages() { 2264 return packages().toArray(Package[]::new); 2265 } 2266 2267 /** 2268 * Finds a package by <a href="#binary-name">name</a> in this class loader and its ancestors. 2269 * <p> 2270 * If this class loader defines a {@code Package} of the given name, 2271 * the {@code Package} is returned. Otherwise, the ancestors of 2272 * this class loader are searched recursively (parent by parent) 2273 * for a {@code Package} of the given name. 2274 * 2275 * @apiNote The {@link #getPlatformClassLoader() platform class loader} 2276 * may delegate to the application class loader but the application class 2277 * loader is not its ancestor. When invoked on the platform class loader, 2278 * this method will not find packages defined to the application 2279 * class loader. 2280 * 2281 * @param name 2282 * The <a href="#binary-name">package name</a> 2283 * 2284 * @return The {@code Package} of the given name that has been defined by 2285 * this class loader or its ancestors, or {@code null} if not found. 2286 * 2287 * @throws NullPointerException 2288 * if {@code name} is {@code null}. 2289 * 2290 * @deprecated 2291 * If multiple class loaders delegate to each other and define classes 2292 * with the same package name, and one such loader relies on the lookup 2293 * behavior of {@code getPackage} to return a {@code Package} from 2294 * a parent loader, then the properties exposed by the {@code Package} 2295 * may not be as expected in the rest of the program. 2296 * For example, the {@code Package} will only expose annotations from the 2297 * {@code package-info.class} file defined by the parent loader, even if 2298 * annotations exist in a {@code package-info.class} file defined by 2299 * a child loader. A more robust approach is to use the 2300 * {@link ClassLoader#getDefinedPackage} method which returns 2301 * a {@code Package} for the specified class loader. 2302 * 2303 * @see ClassLoader#getDefinedPackage(String) 2304 * 2305 * @since 1.2 2306 * @revised 9 2307 * @spec JPMS 2308 */ 2309 @Deprecated(since="9") 2310 protected Package getPackage(String name) { 2311 Package pkg = getDefinedPackage(name); 2312 if (pkg == null) { 2313 if (parent != null) { 2314 pkg = parent.getPackage(name); 2315 } else { 2316 pkg = BootLoader.getDefinedPackage(name); 2317 } 2318 } 2319 return pkg; 2320 } 2321 2322 /** 2323 * Returns all of the {@code Package}s that have been defined by 2324 * this class loader and its ancestors. The returned array may contain 2325 * more than one {@code Package} object of the same package name, each 2326 * defined by a different class loader in the class loader hierarchy. 2327 * 2328 * @apiNote The {@link #getPlatformClassLoader() platform class loader} 2329 * may delegate to the application class loader. In other words, 2330 * packages in modules defined to the application class loader may be 2331 * visible to the platform class loader. On the other hand, 2332 * the application class loader is not its ancestor and hence 2333 * when invoked on the platform class loader, this method will not 2334 * return any packages defined to the application class loader. 2335 * 2336 * @return The array of {@code Package} objects that have been defined by 2337 * this class loader and its ancestors 2338 * 2339 * @see ClassLoader#getDefinedPackages() 2340 * 2341 * @since 1.2 2342 * @revised 9 2343 * @spec JPMS 2344 */ 2345 protected Package[] getPackages() { 2346 Stream<Package> pkgs = packages(); 2347 ClassLoader ld = parent; 2348 while (ld != null) { 2349 pkgs = Stream.concat(ld.packages(), pkgs); 2350 ld = ld.parent; 2351 } 2352 return Stream.concat(BootLoader.packages(), pkgs) 2353 .toArray(Package[]::new); 2354 } 2355 2356 2357 2358 // package-private 2359 2360 /** 2361 * Returns a stream of Packages defined in this class loader 2362 */ 2363 Stream<Package> packages() { 2364 return packages.values().stream() 2365 .map(p -> definePackage(p.packageName(), p.module())); 2366 } 2367 2368 // -- Native library access -- 2369 2370 /** 2371 * Returns the absolute path name of a native library. The VM invokes this 2372 * method to locate the native libraries that belong to classes loaded with 2373 * this class loader. If this method returns {@code null}, the VM 2374 * searches the library along the path specified as the 2375 * "{@code java.library.path}" property. 2376 * 2377 * @param libname 2378 * The library name 2379 * 2380 * @return The absolute path of the native library 2381 * 2382 * @see System#loadLibrary(String) 2383 * @see System#mapLibraryName(String) 2384 * 2385 * @since 1.2 2386 */ 2387 protected String findLibrary(String libname) { 2388 return null; 2389 } 2390 2391 /** 2392 * The inner class NativeLibrary denotes a loaded native library instance. 2393 * Every classloader contains a vector of loaded native libraries in the 2394 * private field {@code nativeLibraries}. The native libraries loaded 2395 * into the system are entered into the {@code systemNativeLibraries} 2396 * vector. 2397 * 2398 * <p> Every native library requires a particular version of JNI. This is 2399 * denoted by the private {@code jniVersion} field. This field is set by 2400 * the VM when it loads the library, and used by the VM to pass the correct 2401 * version of JNI to the native methods. </p> 2402 * 2403 * @see ClassLoader 2404 * @since 1.2 2405 */ 2406 static class NativeLibrary { 2407 // the class from which the library is loaded, also indicates 2408 // the loader this native library belongs. 2409 final Class<?> fromClass; 2410 // the canonicalized name of the native library. 2411 // or static library name 2412 final String name; 2413 // Indicates if the native library is linked into the VM 2414 final boolean isBuiltin; 2415 2416 // opaque handle to native library, used in native code. 2417 long handle; 2418 // the version of JNI environment the native library requires. 2419 int jniVersion; 2420 2421 native boolean load0(String name, boolean isBuiltin); 2422 2423 native long findEntry(String name); 2424 2425 NativeLibrary(Class<?> fromClass, String name, boolean isBuiltin) { 2426 this.name = name; 2427 this.fromClass = fromClass; 2428 this.isBuiltin = isBuiltin; 2429 } 2430 2431 /* 2432 * Loads the native library and registers for cleanup when its 2433 * associated class loader is unloaded 2434 */ 2435 boolean load() { 2436 if (handle != 0) { 2437 throw new InternalError("Native library " + name + " has been loaded"); 2438 } 2439 2440 if (!load0(name, isBuiltin)) return false; 2441 2442 // register the class loader for cleanup when unloaded 2443 // builtin class loaders are never unloaded 2444 ClassLoader loader = fromClass.getClassLoader(); 2445 if (loader != null && 2446 loader != getBuiltinPlatformClassLoader() && 2447 loader != getBuiltinAppClassLoader()) { 2448 CleanerFactory.cleaner().register(loader, 2449 new Unloader(name, handle, isBuiltin)); 2450 } 2451 return true; 2452 } 2453 2454 static boolean loadLibrary(Class<?> fromClass, String name, boolean isBuiltin) { 2455 ClassLoader loader = 2456 fromClass == null ? null : fromClass.getClassLoader(); 2457 2458 synchronized (loadedLibraryNames) { 2459 Map<String, NativeLibrary> libs = 2460 loader != null ? loader.nativeLibraries() : systemNativeLibraries(); 2461 if (libs.containsKey(name)) { 2462 return true; 2463 } 2464 2465 if (loadedLibraryNames.contains(name)) { 2466 throw new UnsatisfiedLinkError("Native Library " + name + 2467 " already loaded in another classloader"); 2468 } 2469 2470 /* 2471 * When a library is being loaded, JNI_OnLoad function can cause 2472 * another loadLibrary invocation that should succeed. 2473 * 2474 * We use a static stack to hold the list of libraries we are 2475 * loading because this can happen only when called by the 2476 * same thread because Runtime.load and Runtime.loadLibrary 2477 * are synchronous. 2478 * 2479 * If there is a pending load operation for the library, we 2480 * immediately return success; otherwise, we raise 2481 * UnsatisfiedLinkError. 2482 */ 2483 for (NativeLibrary lib : nativeLibraryContext) { 2484 if (name.equals(lib.name)) { 2485 if (loader == lib.fromClass.getClassLoader()) { 2486 return true; 2487 } else { 2488 throw new UnsatisfiedLinkError("Native Library " + 2489 name + " is being loaded in another classloader"); 2490 } 2491 } 2492 } 2493 NativeLibrary lib = new NativeLibrary(fromClass, name, isBuiltin); 2494 // load the native library 2495 nativeLibraryContext.push(lib); 2496 try { 2497 if (!lib.load()) return false; 2498 } finally { 2499 nativeLibraryContext.pop(); 2500 } 2501 // register the loaded native library 2502 loadedLibraryNames.add(name); 2503 libs.put(name, lib); 2504 } 2505 return true; 2506 } 2507 2508 // Invoked in the VM to determine the context class in JNI_OnLoad 2509 // and JNI_OnUnload 2510 static Class<?> getFromClass() { 2511 return nativeLibraryContext.peek().fromClass; 2512 } 2513 2514 // native libraries being loaded 2515 static Deque<NativeLibrary> nativeLibraryContext = new ArrayDeque<>(8); 2516 2517 /* 2518 * The run() method will be invoked when this class loader becomes 2519 * phantom reachable to unload the native library. 2520 */ 2521 static class Unloader implements Runnable { 2522 // This represents the context when a native library is unloaded 2523 // and getFromClass() will return null, 2524 static final NativeLibrary UNLOADER = 2525 new NativeLibrary(null, "dummy", false); 2526 final String name; 2527 final long handle; 2528 final boolean isBuiltin; 2529 2530 Unloader(String name, long handle, boolean isBuiltin) { 2531 if (handle == 0) { 2532 throw new IllegalArgumentException( 2533 "Invalid handle for native library " + name); 2534 } 2535 2536 this.name = name; 2537 this.handle = handle; 2538 this.isBuiltin = isBuiltin; 2539 } 2540 2541 @Override 2542 public void run() { 2543 synchronized (loadedLibraryNames) { 2544 /* remove the native library name */ 2545 loadedLibraryNames.remove(name); 2546 nativeLibraryContext.push(UNLOADER); 2547 try { 2548 unload(name, isBuiltin, handle); 2549 } finally { 2550 nativeLibraryContext.pop(); 2551 } 2552 2553 } 2554 } 2555 } 2556 2557 // JNI FindClass expects the caller class if invoked from JNI_OnLoad 2558 // and JNI_OnUnload is NativeLibrary class 2559 static native void unload(String name, boolean isBuiltin, long handle); 2560 } 2561 2562 // The paths searched for libraries 2563 private static String usr_paths[]; 2564 private static String sys_paths[]; 2565 2566 private static String[] initializePath(String propName) { 2567 String ldPath = System.getProperty(propName, ""); 2568 int ldLen = ldPath.length(); 2569 char ps = File.pathSeparatorChar; 2570 int psCount = 0; 2571 2572 if (ClassLoaderHelper.allowsQuotedPathElements && 2573 ldPath.indexOf('\"') >= 0) { 2574 // First, remove quotes put around quoted parts of paths. 2575 // Second, use a quotation mark as a new path separator. 2576 // This will preserve any quoted old path separators. 2577 char[] buf = new char[ldLen]; 2578 int bufLen = 0; 2579 for (int i = 0; i < ldLen; ++i) { 2580 char ch = ldPath.charAt(i); 2581 if (ch == '\"') { 2582 while (++i < ldLen && 2583 (ch = ldPath.charAt(i)) != '\"') { 2584 buf[bufLen++] = ch; 2585 } 2586 } else { 2587 if (ch == ps) { 2588 psCount++; 2589 ch = '\"'; 2590 } 2591 buf[bufLen++] = ch; 2592 } 2593 } 2594 ldPath = new String(buf, 0, bufLen); 2595 ldLen = bufLen; 2596 ps = '\"'; 2597 } else { 2598 for (int i = ldPath.indexOf(ps); i >= 0; 2599 i = ldPath.indexOf(ps, i + 1)) { 2600 psCount++; 2601 } 2602 } 2603 2604 String[] paths = new String[psCount + 1]; 2605 int pathStart = 0; 2606 for (int j = 0; j < psCount; ++j) { 2607 int pathEnd = ldPath.indexOf(ps, pathStart); 2608 paths[j] = (pathStart < pathEnd) ? 2609 ldPath.substring(pathStart, pathEnd) : "."; 2610 pathStart = pathEnd + 1; 2611 } 2612 paths[psCount] = (pathStart < ldLen) ? 2613 ldPath.substring(pathStart, ldLen) : "."; 2614 return paths; 2615 } 2616 2617 // Invoked in the java.lang.Runtime class to implement load and loadLibrary. 2618 static void loadLibrary(Class<?> fromClass, String name, 2619 boolean isAbsolute) { 2620 ClassLoader loader = 2621 (fromClass == null) ? null : fromClass.getClassLoader(); 2622 if (sys_paths == null) { 2623 usr_paths = initializePath("java.library.path"); 2624 sys_paths = initializePath("sun.boot.library.path"); 2625 } 2626 if (isAbsolute) { 2627 if (loadLibrary0(fromClass, new File(name))) { 2628 return; 2629 } 2630 throw new UnsatisfiedLinkError("Can't load library: " + name); 2631 } 2632 if (loader != null) { 2633 String libfilename = loader.findLibrary(name); 2634 if (libfilename != null) { 2635 File libfile = new File(libfilename); 2636 if (!libfile.isAbsolute()) { 2637 throw new UnsatisfiedLinkError( 2638 "ClassLoader.findLibrary failed to return an absolute path: " + libfilename); 2639 } 2640 if (loadLibrary0(fromClass, libfile)) { 2641 return; 2642 } 2643 throw new UnsatisfiedLinkError("Can't load " + libfilename); 2644 } 2645 } 2646 for (String sys_path : sys_paths) { 2647 File libfile = new File(sys_path, System.mapLibraryName(name)); 2648 if (loadLibrary0(fromClass, libfile)) { 2649 return; 2650 } 2651 libfile = ClassLoaderHelper.mapAlternativeName(libfile); 2652 if (libfile != null && loadLibrary0(fromClass, libfile)) { 2653 return; 2654 } 2655 } 2656 if (loader != null) { 2657 for (String usr_path : usr_paths) { 2658 File libfile = new File(usr_path, System.mapLibraryName(name)); 2659 if (loadLibrary0(fromClass, libfile)) { 2660 return; 2661 } 2662 libfile = ClassLoaderHelper.mapAlternativeName(libfile); 2663 if (libfile != null && loadLibrary0(fromClass, libfile)) { 2664 return; 2665 } 2666 } 2667 } 2668 // Oops, it failed 2669 throw new UnsatisfiedLinkError("no " + name + 2670 " in java.library.path: " + Arrays.toString(usr_paths)); 2671 } 2672 2673 private static native String findBuiltinLib(String name); 2674 2675 private static boolean loadLibrary0(Class<?> fromClass, final File file) { 2676 // Check to see if we're attempting to access a static library 2677 String name = findBuiltinLib(file.getName()); 2678 boolean isBuiltin = (name != null); 2679 if (!isBuiltin) { 2680 name = AccessController.doPrivileged( 2681 new PrivilegedAction<>() { 2682 public String run() { 2683 try { 2684 return file.exists() ? file.getCanonicalPath() : null; 2685 } catch (IOException e) { 2686 return null; 2687 } 2688 } 2689 }); 2690 if (name == null) { 2691 return false; 2692 } 2693 } 2694 return NativeLibrary.loadLibrary(fromClass, name, isBuiltin); 2695 } 2696 2697 /* 2698 * Invoked in the VM class linking code. 2699 */ 2700 private static long findNative(ClassLoader loader, String entryName) { 2701 Map<String, NativeLibrary> libs = 2702 loader != null ? loader.nativeLibraries() : systemNativeLibraries(); 2703 if (libs.isEmpty()) 2704 return 0; 2705 2706 // the native libraries map may be updated in another thread 2707 // when a native library is being loaded. No symbol will be 2708 // searched from it yet. 2709 for (NativeLibrary lib : libs.values()) { 2710 long entry = lib.findEntry(entryName); 2711 if (entry != 0) return entry; 2712 } 2713 return 0; 2714 } 2715 2716 // All native library names we've loaded. 2717 // This also serves as the lock to obtain nativeLibraries 2718 // and write to nativeLibraryContext. 2719 private static final Set<String> loadedLibraryNames = new HashSet<>(); 2720 2721 // Native libraries belonging to system classes. 2722 private static volatile Map<String, NativeLibrary> systemNativeLibraries; 2723 2724 // Native libraries associated with the class loader. 2725 private volatile Map<String, NativeLibrary> nativeLibraries; 2726 2727 /* 2728 * Returns the native libraries map associated with bootstrap class loader 2729 * This method will create the map at the first time when called. 2730 */ 2731 private static Map<String, NativeLibrary> systemNativeLibraries() { 2732 Map<String, NativeLibrary> libs = systemNativeLibraries; 2733 if (libs == null) { 2734 synchronized (loadedLibraryNames) { 2735 libs = systemNativeLibraries; 2736 if (libs == null) { 2737 libs = systemNativeLibraries = new ConcurrentHashMap<>(); 2738 } 2739 } 2740 } 2741 return libs; 2742 } 2743 2744 /* 2745 * Returns the native libraries map associated with this class loader 2746 * This method will create the map at the first time when called. 2747 */ 2748 private Map<String, NativeLibrary> nativeLibraries() { 2749 Map<String, NativeLibrary> libs = nativeLibraries; 2750 if (libs == null) { 2751 synchronized (loadedLibraryNames) { 2752 libs = nativeLibraries; 2753 if (libs == null) { 2754 libs = nativeLibraries = new ConcurrentHashMap<>(); 2755 } 2756 } 2757 } 2758 return libs; 2759 } 2760 2761 // -- Assertion management -- 2762 2763 final Object assertionLock; 2764 2765 // The default toggle for assertion checking. 2766 // @GuardedBy("assertionLock") 2767 private boolean defaultAssertionStatus = false; 2768 2769 // Maps String packageName to Boolean package default assertion status Note 2770 // that the default package is placed under a null map key. If this field 2771 // is null then we are delegating assertion status queries to the VM, i.e., 2772 // none of this ClassLoader's assertion status modification methods have 2773 // been invoked. 2774 // @GuardedBy("assertionLock") 2775 private Map<String, Boolean> packageAssertionStatus = null; 2776 2777 // Maps String fullyQualifiedClassName to Boolean assertionStatus If this 2778 // field is null then we are delegating assertion status queries to the VM, 2779 // i.e., none of this ClassLoader's assertion status modification methods 2780 // have been invoked. 2781 // @GuardedBy("assertionLock") 2782 Map<String, Boolean> classAssertionStatus = null; 2783 2784 /** 2785 * Sets the default assertion status for this class loader. This setting 2786 * determines whether classes loaded by this class loader and initialized 2787 * in the future will have assertions enabled or disabled by default. 2788 * This setting may be overridden on a per-package or per-class basis by 2789 * invoking {@link #setPackageAssertionStatus(String, boolean)} or {@link 2790 * #setClassAssertionStatus(String, boolean)}. 2791 * 2792 * @param enabled 2793 * {@code true} if classes loaded by this class loader will 2794 * henceforth have assertions enabled by default, {@code false} 2795 * if they will have assertions disabled by default. 2796 * 2797 * @since 1.4 2798 */ 2799 public void setDefaultAssertionStatus(boolean enabled) { 2800 synchronized (assertionLock) { 2801 if (classAssertionStatus == null) 2802 initializeJavaAssertionMaps(); 2803 2804 defaultAssertionStatus = enabled; 2805 } 2806 } 2807 2808 /** 2809 * Sets the package default assertion status for the named package. The 2810 * package default assertion status determines the assertion status for 2811 * classes initialized in the future that belong to the named package or 2812 * any of its "subpackages". 2813 * 2814 * <p> A subpackage of a package named p is any package whose name begins 2815 * with "{@code p.}". For example, {@code javax.swing.text} is a 2816 * subpackage of {@code javax.swing}, and both {@code java.util} and 2817 * {@code java.lang.reflect} are subpackages of {@code java}. 2818 * 2819 * <p> In the event that multiple package defaults apply to a given class, 2820 * the package default pertaining to the most specific package takes 2821 * precedence over the others. For example, if {@code javax.lang} and 2822 * {@code javax.lang.reflect} both have package defaults associated with 2823 * them, the latter package default applies to classes in 2824 * {@code javax.lang.reflect}. 2825 * 2826 * <p> Package defaults take precedence over the class loader's default 2827 * assertion status, and may be overridden on a per-class basis by invoking 2828 * {@link #setClassAssertionStatus(String, boolean)}. </p> 2829 * 2830 * @param packageName 2831 * The name of the package whose package default assertion status 2832 * is to be set. A {@code null} value indicates the unnamed 2833 * package that is "current" 2834 * (see section 7.4.2 of 2835 * <cite>The Java™ Language Specification</cite>.) 2836 * 2837 * @param enabled 2838 * {@code true} if classes loaded by this classloader and 2839 * belonging to the named package or any of its subpackages will 2840 * have assertions enabled by default, {@code false} if they will 2841 * have assertions disabled by default. 2842 * 2843 * @since 1.4 2844 */ 2845 public void setPackageAssertionStatus(String packageName, 2846 boolean enabled) { 2847 synchronized (assertionLock) { 2848 if (packageAssertionStatus == null) 2849 initializeJavaAssertionMaps(); 2850 2851 packageAssertionStatus.put(packageName, enabled); 2852 } 2853 } 2854 2855 /** 2856 * Sets the desired assertion status for the named top-level class in this 2857 * class loader and any nested classes contained therein. This setting 2858 * takes precedence over the class loader's default assertion status, and 2859 * over any applicable per-package default. This method has no effect if 2860 * the named class has already been initialized. (Once a class is 2861 * initialized, its assertion status cannot change.) 2862 * 2863 * <p> If the named class is not a top-level class, this invocation will 2864 * have no effect on the actual assertion status of any class. </p> 2865 * 2866 * @param className 2867 * The fully qualified class name of the top-level class whose 2868 * assertion status is to be set. 2869 * 2870 * @param enabled 2871 * {@code true} if the named class is to have assertions 2872 * enabled when (and if) it is initialized, {@code false} if the 2873 * class is to have assertions disabled. 2874 * 2875 * @since 1.4 2876 */ 2877 public void setClassAssertionStatus(String className, boolean enabled) { 2878 synchronized (assertionLock) { 2879 if (classAssertionStatus == null) 2880 initializeJavaAssertionMaps(); 2881 2882 classAssertionStatus.put(className, enabled); 2883 } 2884 } 2885 2886 /** 2887 * Sets the default assertion status for this class loader to 2888 * {@code false} and discards any package defaults or class assertion 2889 * status settings associated with the class loader. This method is 2890 * provided so that class loaders can be made to ignore any command line or 2891 * persistent assertion status settings and "start with a clean slate." 2892 * 2893 * @since 1.4 2894 */ 2895 public void clearAssertionStatus() { 2896 /* 2897 * Whether or not "Java assertion maps" are initialized, set 2898 * them to empty maps, effectively ignoring any present settings. 2899 */ 2900 synchronized (assertionLock) { 2901 classAssertionStatus = new HashMap<>(); 2902 packageAssertionStatus = new HashMap<>(); 2903 defaultAssertionStatus = false; 2904 } 2905 } 2906 2907 /** 2908 * Returns the assertion status that would be assigned to the specified 2909 * class if it were to be initialized at the time this method is invoked. 2910 * If the named class has had its assertion status set, the most recent 2911 * setting will be returned; otherwise, if any package default assertion 2912 * status pertains to this class, the most recent setting for the most 2913 * specific pertinent package default assertion status is returned; 2914 * otherwise, this class loader's default assertion status is returned. 2915 * </p> 2916 * 2917 * @param className 2918 * The fully qualified class name of the class whose desired 2919 * assertion status is being queried. 2920 * 2921 * @return The desired assertion status of the specified class. 2922 * 2923 * @see #setClassAssertionStatus(String, boolean) 2924 * @see #setPackageAssertionStatus(String, boolean) 2925 * @see #setDefaultAssertionStatus(boolean) 2926 * 2927 * @since 1.4 2928 */ 2929 boolean desiredAssertionStatus(String className) { 2930 synchronized (assertionLock) { 2931 // assert classAssertionStatus != null; 2932 // assert packageAssertionStatus != null; 2933 2934 // Check for a class entry 2935 Boolean result = classAssertionStatus.get(className); 2936 if (result != null) 2937 return result.booleanValue(); 2938 2939 // Check for most specific package entry 2940 int dotIndex = className.lastIndexOf('.'); 2941 if (dotIndex < 0) { // default package 2942 result = packageAssertionStatus.get(null); 2943 if (result != null) 2944 return result.booleanValue(); 2945 } 2946 while(dotIndex > 0) { 2947 className = className.substring(0, dotIndex); 2948 result = packageAssertionStatus.get(className); 2949 if (result != null) 2950 return result.booleanValue(); 2951 dotIndex = className.lastIndexOf('.', dotIndex-1); 2952 } 2953 2954 // Return the classloader default 2955 return defaultAssertionStatus; 2956 } 2957 } 2958 2959 // Set up the assertions with information provided by the VM. 2960 // Note: Should only be called inside a synchronized block 2961 private void initializeJavaAssertionMaps() { 2962 // assert Thread.holdsLock(assertionLock); 2963 2964 classAssertionStatus = new HashMap<>(); 2965 packageAssertionStatus = new HashMap<>(); 2966 AssertionStatusDirectives directives = retrieveDirectives(); 2967 2968 for(int i = 0; i < directives.classes.length; i++) 2969 classAssertionStatus.put(directives.classes[i], 2970 directives.classEnabled[i]); 2971 2972 for(int i = 0; i < directives.packages.length; i++) 2973 packageAssertionStatus.put(directives.packages[i], 2974 directives.packageEnabled[i]); 2975 2976 defaultAssertionStatus = directives.deflt; 2977 } 2978 2979 // Retrieves the assertion directives from the VM. 2980 private static native AssertionStatusDirectives retrieveDirectives(); 2981 2982 2983 // -- Misc -- 2984 2985 /** 2986 * Returns the ConcurrentHashMap used as a storage for ClassLoaderValue(s) 2987 * associated with this ClassLoader, creating it if it doesn't already exist. 2988 */ 2989 ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap() { 2990 ConcurrentHashMap<?, ?> map = classLoaderValueMap; 2991 if (map == null) { 2992 map = new ConcurrentHashMap<>(); 2993 boolean set = trySetObjectField("classLoaderValueMap", map); 2994 if (!set) { 2995 // beaten by someone else 2996 map = classLoaderValueMap; 2997 } 2998 } 2999 return map; 3000 } 3001 3002 // the storage for ClassLoaderValue(s) associated with this ClassLoader 3003 private volatile ConcurrentHashMap<?, ?> classLoaderValueMap; 3004 3005 /** 3006 * Attempts to atomically set a volatile field in this object. Returns 3007 * {@code true} if not beaten by another thread. Avoids the use of 3008 * AtomicReferenceFieldUpdater in this class. 3009 */ 3010 private boolean trySetObjectField(String name, Object obj) { 3011 Unsafe unsafe = Unsafe.getUnsafe(); 3012 Class<?> k = ClassLoader.class; 3013 long offset; 3014 offset = unsafe.objectFieldOffset(k, name); 3015 return unsafe.compareAndSetReference(this, offset, null, obj); 3016 } 3017 } 3018 3019 /* 3020 * A utility class that will enumerate over an array of enumerations. 3021 */ 3022 final class CompoundEnumeration<E> implements Enumeration<E> { 3023 private final Enumeration<E>[] enums; 3024 private int index; 3025 3026 public CompoundEnumeration(Enumeration<E>[] enums) { 3027 this.enums = enums; 3028 } 3029 3030 private boolean next() { 3031 while (index < enums.length) { 3032 if (enums[index] != null && enums[index].hasMoreElements()) { 3033 return true; 3034 } 3035 index++; 3036 } 3037 return false; 3038 } 3039 3040 public boolean hasMoreElements() { 3041 return next(); 3042 } 3043 3044 public E nextElement() { 3045 if (!next()) { 3046 throw new NoSuchElementException(); 3047 } 3048 return enums[index].nextElement(); 3049 } 3050 }